gst/gstpipeline.c: Only try to select a different pipeline clock when we went back to

gst/gstpipeline.c: Only try to select a different pipeline clock when we went back to

Original commit message from CVS:
* gst/gstpipeline.c: (reset_stream_time),
(gst_pipeline_change_state), (gst_pipeline_set_new_stream_time):
Only try to select a different pipeline clock when we went back to
PAUSED and not when we merely got flushed.