[clang] [PowerPC] Fix use of FPSCR builtins in smmintrin.h (PR #67299)

[Stefan Pintilie via cfe-commits]

================
@@ -68,10 +68,10 @@ extern __inline __m128d
     __asm__("mffsce %0" : "=f"(__fpscr_save.__fr));
     __enables_save.__fpscr = __fpscr_save.__fpscr & 0xf8;
 #else
-    __fpscr_save.__fr = __builtin_mffs();
+    __fpscr_save.__fr = __builtin_ppc_mffs();
----------------
stefanp-ibm wrote:

I don't believe that this builtin needs to be renamed. On clang both `__builtin_mffs` and `__builtin_ppc_mffs` work.

Also, this is the same for the other 3 builtins.

When you update these names you will probably also have to update the `ppc-smmintrin.c` test as well.

https://github.com/llvm/llvm-project/pull/67299