[Support] Include intrin.h for MSVC intrinsics in xxhash.cpp

`__umulh` added in llvm#95863
requires `intrin.h`, make sure to include it.

Author: bnbarham

llvm/lib/Support/xxhash.cpp

@@ -60,6 +60,10 @@
 #include <arm_neon.h>
 #endif
 
+#if defined(_MSC_VER)
+#include <intrin.h>
+#endif
+
 using namespace llvm;
 using namespace support;