Use ifunc to dynamically dispatch libc routines for x86

Test: run bionic unit test in aosp_cf_x86_phone emulator
Change-Id: Ib0c0de37cd38d24bfce2dfbe35b8fd8edff004af
diff --git a/libc/arch-x86/generic/string/memcmp.S b/libc/arch-x86/generic/string/memcmp.S
index ef36b4f..1d327c7 100644
--- a/libc/arch-x86/generic/string/memcmp.S
+++ b/libc/arch-x86/generic/string/memcmp.S
@@ -6,7 +6,7 @@
 
 #include <private/bionic_asm.h>
 
-ENTRY(memcmp)
+ENTRY(memcmp_generic)
 	pushl	%edi
 	pushl	%esi
 	movl	12(%esp),%edi
@@ -41,4 +41,4 @@
 	popl	%esi
 	popl	%edi
 	ret
-END(memcmp)
+END(memcmp_generic)