hardware: Move cpuid include and make conditional (#1202)

Summary:
Fixes compilation on non x86.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Pull Request resolved: https://github.com/facebook/folly/pull/1202

Differential Revision: D16760427

Pulled By: yfeldblum

fbshipit-source-id: 6f31d5a17b9fe9c1f91d884eb94967ba06756f3e

folly/synchronization/detail/Hardware.cpp

@@ -23,12 +23,6 @@
 
 #include <glog/logging.h>
 
-#if defined(__GNUC__) || defined(__clang__)
-#include <cpuid.h>
-#elif defined(_MSC_VER)
-#include <intrin.h>
-#endif
-
 #if FOLLY_X64 && defined(__RTM__)
 #include <folly/lang/Assume.h>
 #include <immintrin.h>
@@ -36,6 +30,14 @@
 #elif FOLLY_X64
 #endif
 
+#if FOLLY_RTM_SUPPORT
+#if defined(__GNUC__) || defined(__clang__)
+#include <cpuid.h>
+#elif defined(_MSC_VER)
+#include <intrin.h>
+#endif
+#endif
+
 namespace folly {
 namespace hardware {