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-arm/krait/bionic/memset.S b/libc/arch-arm/krait/bionic/memset.S
index 0264dd3..81ba74b 100644
--- a/libc/arch-arm/krait/bionic/memset.S
+++ b/libc/arch-arm/krait/bionic/memset.S
@@ -40,7 +40,7 @@
 
 ENTRY(__memset_chk)
         cmp         r2, r3
-        bls         .L_done
+        bls         memset
 
         // Preserve lr for backtrace.
         push        {lr}
@@ -50,14 +50,6 @@
         bl          __memset_chk_fail
 END(__memset_chk)
 
-ENTRY(bzero)
-        mov     r2, r1
-        mov     r1, #0
-
-.L_done:
-        // Fall through to memset...
-END(bzero)
-
 /* memset() returns its first argument.  */
 ENTRY(memset)
         mov         r3, r0