[clang] Fix name conflict with sys/mac.h on AIX (#88644)

Fixes clang-ppc64-aix bot failure after #88559
(0a6f6df)
https://lab.llvm.org/buildbot/#/builders/214/builds/11887

---------

Co-authored-by: Joseph Huber <huberjn@outlook.com>

Author: Endilll

clang/include/clang/Basic/Cuda.h

@@ -50,6 +50,10 @@ const char *CudaVersionToString(CudaVersion V);
 // Input is "Major.Minor"
 CudaVersion CudaStringToVersion(const llvm::Twine &S);
 
+// We have a name conflict with sys/mac.h on AIX
+#ifdef SM_32
+#undef SM_32
+#endif
 enum class CudaArch {
   UNUSED,
   UNKNOWN,