ext/jpeg/gstjpegdec.c: After a failed buffer alloc, we need to abort the jpeg decoding (it started when parsing heade...

Original commit message from CVS:
* ext/jpeg/gstjpegdec.c: (gst_jpeg_dec_chain):
After a failed buffer alloc, we need to abort the jpeg decoding (it
started when parsing headers to figure out how many bytes we need
to request downstream).