ext/ogg/gstoggmux.c: Don't generate out-of-order timestamps from oggmux, instead clamp output timestamps to be >= the...

Original commit message from CVS:
* ext/ogg/gstoggmux.c: (gst_ogg_mux_clear),
(gst_ogg_mux_push_buffer):
Don't generate out-of-order timestamps from oggmux, instead clamp
output timestamps to be >= the previously output ts.
Fixes #355595