Add empty semaphore Macro for non-x86 archs

Summary: When people using Static Tracepoint with Semaphore, they'll need to define / declare it. That would cause error on non-supported platforms. This Diff adds empty statement for them.

Reviewed By: myreg

Differential Revision: D8706499

fbshipit-source-id: 2978faf08c451d19e44156308d896e7cac83fcc7

folly/tracing/StaticTracepoint.h

@@ -40,5 +40,6 @@
   do {                                                \
   } while (0)
 #define FOLLY_SDT_IS_ENABLED(provider, name) (false)
-
+#define FOLLY_SDT_DEFINE_SEMAPHORE(provider, name)
+#define FOLLY_SDT_DECLARE_SEMAPHORE(provider, name)
 #endif