Remove optimized code for bzero, which was removed from POSIX in 2008.

I'll come back for the last bcopy remnant...

Bug: http://b/26407170
Change-Id: Iabfeb95fc8a4b4b3992e3cc209ec5221040e7c26
diff --git a/libc/arch-x86/atom/atom.mk b/libc/arch-x86/atom/atom.mk
index 1afabac..34e4c58 100644
--- a/libc/arch-x86/atom/atom.mk
+++ b/libc/arch-x86/atom/atom.mk
@@ -1,5 +1,4 @@
 libc_bionic_src_files_x86 += \
-    arch-x86/atom/string/sse2-bzero-atom.S \
     arch-x86/atom/string/sse2-memset-atom.S \
     arch-x86/atom/string/sse2-strlen-atom.S \
     arch-x86/atom/string/ssse3-bcopy-atom.S \
@@ -15,7 +14,6 @@
 
 libc_bionic_src_files_exclude_x86 += \
     arch-x86/silvermont/string/sse2-bcopy-slm.S \
-    arch-x86/silvermont/string/sse2-bzero-slm.S \
     arch-x86/silvermont/string/sse2-memcpy-slm.S \
     arch-x86/silvermont/string/sse2-memmove-slm.S \
     arch-x86/silvermont/string/sse2-memset-slm.S \
diff --git a/libc/arch-x86/atom/string/sse2-bzero-atom.S b/libc/arch-x86/atom/string/sse2-bzero-atom.S
deleted file mode 100644
index 0ddc499..0000000
--- a/libc/arch-x86/atom/string/sse2-bzero-atom.S
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
-Copyright (c) 2010, Intel Corporation
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-    * Redistributions of source code must retain the above copyright notice,
-    * this list of conditions and the following disclaimer.
-
-    * Redistributions in binary form must reproduce the above copyright notice,
-    * this list of conditions and the following disclaimer in the documentation
-    * and/or other materials provided with the distribution.
-
-    * Neither the name of Intel Corporation nor the names of its contributors
-    * may be used to endorse or promote products derived from this software
-    * without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
-ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
-ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-#define USE_AS_BZERO
-#define MEMSET  bzero
-#include "sse2-memset-atom.S"
diff --git a/libc/arch-x86/atom/string/sse2-memset-atom.S b/libc/arch-x86/atom/string/sse2-memset-atom.S
index b0963a1..e8ceee1 100644
--- a/libc/arch-x86/atom/string/sse2-memset-atom.S
+++ b/libc/arch-x86/atom/string/sse2-memset-atom.S
@@ -84,16 +84,10 @@
 #define PUSH(REG)	pushl REG; CFI_PUSH (REG)
 #define POP(REG)	popl REG; CFI_POP (REG)
 
-#ifdef USE_AS_BZERO
-# define DEST		PARMS
-# define LEN		DEST+4
-# define SETRTNVAL
-#else
-# define DEST		PARMS
-# define CHR		DEST+4
-# define LEN		CHR+4
-# define SETRTNVAL	movl DEST(%esp), %eax
-#endif
+#define DEST		PARMS
+#define CHR		DEST+4
+#define LEN		CHR+4
+#define SETRTNVAL	movl DEST(%esp), %eax
 
 #if (defined SHARED || defined __PIC__)
 # define ENTRANCE	PUSH (%ebx);
@@ -148,16 +142,12 @@
 	ENTRANCE
 
 	movl	LEN(%esp), %ecx
-#ifdef USE_AS_BZERO
-	xor	%eax, %eax
-#else
 	movzbl	CHR(%esp), %eax
 	movb	%al, %ah
 	/* Fill the whole EAX with pattern.  */
 	movl	%eax, %edx
 	shl	$16, %eax
 	or	%edx, %eax
-#endif
 	movl	DEST(%esp), %edx
 	cmp	$32, %ecx
 	jae	L(32bytesormore)
@@ -287,12 +277,8 @@
 /* ECX > 32 and EDX is 4 byte aligned.  */
 L(32bytesormore):
 	/* Fill xmm0 with the pattern.  */
-#ifdef USE_AS_BZERO
-	pxor	%xmm0, %xmm0
-#else
 	movd	%eax, %xmm0
 	pshufd	$0, %xmm0, %xmm0
-#endif
 	testl	$0xf, %edx
 	jz	L(aligned_16)
 /* ECX > 32 and EDX is not 16 byte aligned.  */
diff --git a/libc/arch-x86/silvermont/string/sse2-bzero-slm.S b/libc/arch-x86/silvermont/string/sse2-bzero-slm.S
deleted file mode 100644
index b682ed6..0000000
--- a/libc/arch-x86/silvermont/string/sse2-bzero-slm.S
+++ /dev/null
@@ -1,33 +0,0 @@
-/*
-Copyright (c) 2014, Intel Corporation
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-    * Redistributions of source code must retain the above copyright notice,
-    * this list of conditions and the following disclaimer.
-
-    * Redistributions in binary form must reproduce the above copyright notice,
-    * this list of conditions and the following disclaimer in the documentation
-    * and/or other materials provided with the distribution.
-
-    * Neither the name of Intel Corporation nor the names of its contributors
-    * may be used to endorse or promote products derived from this software
-    * without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
-ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
-ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
-(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
-LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
-ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
-SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
-
-#define USE_AS_BZERO
-#define MEMSET  bzero
-#include "sse2-memset-slm.S"
diff --git a/libc/arch-x86/silvermont/string/sse2-memset-slm.S b/libc/arch-x86/silvermont/string/sse2-memset-slm.S
index c30bf74..489f64e 100644
--- a/libc/arch-x86/silvermont/string/sse2-memset-slm.S
+++ b/libc/arch-x86/silvermont/string/sse2-memset-slm.S
@@ -88,16 +88,10 @@
 #define PUSH(REG)	pushl REG; CFI_PUSH (REG)
 #define POP(REG)	popl REG; CFI_POP (REG)
 
-#ifdef USE_AS_BZERO
-# define DEST		PARMS
-# define LEN		DEST+4
-# define SETRTNVAL
-#else
-# define DEST		PARMS
-# define CHR		DEST+4
-# define LEN		CHR+4
-# define SETRTNVAL	movl DEST(%esp), %eax
-#endif
+#define DEST		PARMS
+#define CHR		DEST+4
+#define LEN		CHR+4
+#define SETRTNVAL	movl DEST(%esp), %eax
 
 #if (defined SHARED || defined __PIC__)
 # define ENTRANCE	PUSH (%ebx);
@@ -154,16 +148,12 @@
 	RETURN
 
 L(1byteormore):
-#ifdef USE_AS_BZERO
-	xor	%eax, %eax
-#else
 	movzbl	CHR(%esp), %eax
 	movb	%al, %ah
 	/* Fill the whole EAX with pattern.  */
 	movl	%eax, %edx
 	shl	 $16, %eax
 	or	%edx, %eax
-#endif
 	movl	DEST(%esp), %edx
 	cmp	$1, %ecx
 	je	L(1byte)
@@ -195,12 +185,8 @@
 
 	ALIGN (4)
 L(16bytesormore):
-#ifdef USE_AS_BZERO
-	pxor	%xmm0, %xmm0
-#else
 	movd	%eax, %xmm0
 	pshufd	$0, %xmm0, %xmm0
-#endif
 
 	cmp	$64, %ecx
 	ja	L(64bytesmore)
diff --git a/libc/arch-x86/x86.mk b/libc/arch-x86/x86.mk
index 1d717aa..9e44a86 100644
--- a/libc/arch-x86/x86.mk
+++ b/libc/arch-x86/x86.mk
@@ -15,7 +15,6 @@
     arch-x86/atom/string/sse2-wcslen-atom.S \
     arch-x86/atom/string/sse2-wcscmp-atom.S \
     arch-x86/silvermont/string/sse2-bcopy-slm.S \
-    arch-x86/silvermont/string/sse2-bzero-slm.S \
     arch-x86/silvermont/string/sse2-memcpy-slm.S \
     arch-x86/silvermont/string/sse2-memmove-slm.S \
     arch-x86/silvermont/string/sse2-memset-slm.S \