gst/gstmessage.c: Don't crash when return location for error/warning debug string is NULL; add fact that return locat...

Original commit message from CVS:
* gst/gstmessage.c: (gst_message_parse_tag),
(gst_message_parse_error), (gst_message_parse_warning):
Don't crash when return location for error/warning debug
string is NULL; add fact that return locations can be
NULL to docs where appropriate.
2 files changed