Fix TIS/TSM in logs

Silences the "is calling TIS/TSM in non-main thread environment"
messages in the log when running a MacOS server as it is a red herring
that causes a lot of issues to be filed.

src/cmd/barriers/barriers.cpp

@@ -39,6 +39,13 @@ main(int argc, char** argv)
     ArchMiscWindows::setInstanceWin32(GetModuleHandle(NULL));
 #endif
 
+#ifdef __APPLE__
+	/* Silence "is calling TIS/TSM in non-main thread environment" as it is a red
+	herring that causes a lot of issues to be filed for the MacOS client/server.
+	*/
+	setenv("OS_ACTIVITY_DT_MODE", "NO", true);
+#endif
+    
     Arch arch;
     arch.init();