[PowerPC] Add nmmintrin.h to copy list

nmmintrin.h was missing in the list of copied ppc_wrappers. No tests
needed since it only includes smmintrin.h.

Author: ecnelises

clang/lib/Headers/CMakeLists.txt

@@ -285,6 +285,7 @@ set(ppc_wrapper_files
   ppc_wrappers/pmmintrin.h
   ppc_wrappers/tmmintrin.h
   ppc_wrappers/smmintrin.h
+  ppc_wrappers/nmmintrin.h
   ppc_wrappers/bmiintrin.h
   ppc_wrappers/bmi2intrin.h
   ppc_wrappers/immintrin.h