wasapi: use FAILED to detect errors

S_FALSE is a valid return value which does not indicate an error.
For example IAudioClient_Stop() returns S_FALSE when it is already stopped.
Use the FAILED macro instead which just checks if an error occured or not.

This fixes spurious warnings when using the wasapisink element.

https://bugzilla.gnome.org/show_bug.cgi?id=796280

sys/wasapi/gstwasapiutil.h

@@ -43,7 +43,7 @@
 /* Standard error path */
 #define HR_FAILED_AND(hr,func,and) \
   do { \
-    if (hr != S_OK) { \
+    if (FAILED (hr)) { \
       gchar *msg = gst_wasapi_util_hresult_to_string (hr); \
       GST_ERROR_OBJECT (self, #func " failed (%x): %s", (guint) hr, msg); \
       g_free (msg); \