Fix Windows macro detection

Summary:
The `__cpuid()` and `__cpuidex()` instructions are only available on
x86 and x64 https://fburl.com/ejw47bcl.

Reported in zstd [Issue#1313](https://github.com/facebook/zstd/issues/1313).

Reviewed By: Orvid

Differential Revision: D9800189

fbshipit-source-id: 8e846d2220e544b16547db16d21c7c7b0e21cefb

folly/CpuId.h

@@ -41,7 +41,7 @@ class CpuId {
   // mode since inlining happens more likely, and it doesn't happen for
   // statically linked binaries which don't depend on the PLT)
   FOLLY_ALWAYS_INLINE CpuId() {
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && (FOLLY_X64 || defined(_M_IX86))
     int reg[4];
     __cpuid(static_cast<int*>(reg), 0);
     const int n = reg[0];