Clean up bcopy cruft.

Also remove some generic x86 assembler that's never built.

Change-Id: Ic126de2eee646b5ba2b6ee549679ba90d67a48bb
diff --git a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S b/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
index 6a8f067..bf9f85d 100644
--- a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
+++ b/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
@@ -73,15 +73,9 @@
 	.size name, .-name
 #endif
 
-#ifdef USE_AS_BCOPY
-# define SRC		PARMS
-# define DEST		SRC+4
-# define LEN		DEST+4
-#else
-# define DEST		PARMS
-# define SRC		DEST+4
-# define LEN		SRC+4
-#endif
+#define DEST		PARMS
+#define SRC		DEST+4
+#define LEN		SRC+4
 
 #define CFI_PUSH(REG)		\
   cfi_adjust_cfa_offset (4);		\