winegstreamer: Enable wg_parser streams on creation.

This patch is motivated by Obduction, which creates a Media Foundation source
and leaves it open arbitrarily long before actually reading samples from it.
Without this patch, we unnecessarily waste CPU, and may reduce graphical
performance by taking CPU time that would otherwise be used on
performance-critical threads.

Signed-off-by: Zebediah Figura <zfigura@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/winegstreamer/wg_parser.c

@@ -1293,6 +1293,13 @@ static NTSTATUS wg_parser_connect(void *args)
                 pthread_cond_wait(&parser->init_cond, &parser->mutex);
             }
         }
+
+        /* Now that we're fully initialized, enable the stream so that further
+         * samples get queued instead of being discarded. We don't actually need
+         * the samples (in particular, the frontend should seek before
+         * attempting to read anything), but we don't want to waste CPU time
+         * trying to decode them. */
+        stream->enabled = true;
     }
 
     pthread_mutex_unlock(&parser->mutex);