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-strncpy-atom.S b/libc/arch-x86/atom/string/ssse3-strncpy-atom.S
index 0948b6d..0c27ffe 100644
--- a/libc/arch-x86/atom/string/ssse3-strncpy-atom.S
+++ b/libc/arch-x86/atom/string/ssse3-strncpy-atom.S
@@ -29,5 +29,5 @@
 */
 
 #define USE_AS_STRNCPY
-#define STRCPY strncpy
+#define STRCPY strncpy_atom
 #include "ssse3-strcpy-atom.S"