shims: correct indirection on Windows

The `_dispatch_sema4_t` type is a pointer to the handle of the semaphore, so we need to indirect through the pointer before using it. This site was incorrectly using it directly.

Author: compnerd

src/shims/lock.c

@@ -308,7 +308,7 @@ _dispatch_sema4_timedwait(_dispatch_sema4_t *sema, dispatch_time_t timeout)
 nsec = _dispatch_timeout(timeout);
 msec = (DWORD)(nsec / (uint64_t)1000000);
 resolution = _push_timer_resolution(msec);
-wait_result = WaitForSingleObject(sema, msec);
+wait_result = WaitForSingleObject(*sema, msec);
 _pop_timer_resolution(resolution);
 return wait_result == WAIT_TIMEOUT;
 }