Threading: add a linker directive for Windows autolinking

This library is pulled into the standard library. Add autolinking
directives to enable the use of the library with static linking without
specifying the system dependencies. This is required to enable the user
to use `-static-stdlib` without having to specify all dependencies.

Author: compnerd

lib/Threading/Win32.cpp

@@ -20,6 +20,8 @@
 #define NOMINMAX
 #include <windows.h>
 
+#pragma comment(lib, "synchronization.lib")
+
 #include "swift/Threading/Errors.h"
 #include "swift/Threading/Impl.h"