add clang's __builtin_ia32_undefX and __builtin_nontemporal_store and __builtin_nontemporal_load

Author: Daniel Kroening

src/ansi-c/clang_builtin_headers.h

@@ -1,3 +1,10 @@
 __gcc_v4sf __builtin_shufflevector(__gcc_v4sf, __gcc_v4sf, ...);
 
+__gcc_v2di __builtin_ia32_undef128(void);
+__gcc_v4di __builtin_ia32_undef256(void);
+__gcc_v8di __builtin_ia32_undef512(void);
+
+void __builtin_nontemporal_store(...);
+void __builtin_nontemporal_load(void *);
+
 int __builtin_flt_rounds(void);