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/atom/string/ssse3-strcmp-atom.S b/libc/arch-x86/atom/string/ssse3-strcmp-atom.S
index ee253b9..08f6d4a 100644
--- a/libc/arch-x86/atom/string/ssse3-strcmp-atom.S
+++ b/libc/arch-x86/atom/string/ssse3-strcmp-atom.S
@@ -108,7 +108,7 @@
 #endif
 
 #ifndef STRCMP
-# define STRCMP strcmp
+# define STRCMP strcmp_ssse3
 #endif
 
 	.section .text.ssse3,"ax",@progbits