Make memcpy memmove

Bug: http://b/63992911
Test: Change BoardConfig.mk and compile for each variant
Change-Id: Ia0cc68d8e90e3316ddb2e9ff1555a009b6a0c5be
diff --git a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S b/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
index bf9f85d..ceada1b 100644
--- a/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
+++ b/libc/arch-x86/silvermont/string/sse2-memmove-slm.S
@@ -67,6 +67,12 @@
 	cfi_startproc
 #endif
 
+#ifndef ALIAS_SYMBOL
+# define ALIAS_SYMBOL(alias, original) \
+	.globl alias; \
+	.equ alias, original
+#endif
+
 #ifndef END
 # define END(name)		\
 	cfi_endproc;		\
@@ -537,3 +543,5 @@
 	jmp	L(mm_recalc_len)
 
 END (MEMMOVE)
+
+ALIAS_SYMBOL(memcpy, MEMMOVE)