gst/subparse/samiparse.c: Some versions of libxml seem to be very picky as to strict...

gst/subparse/samiparse.c: Some versions of libxml seem to be very picky as to strict formatting of the input and neve...

Original commit message from CVS:
* gst/subparse/samiparse.c: (sami_context_push_state),
(sami_context_pop_state), (start_sami_element), (end_sami_element):
Some versions of libxml seem to be very picky as to strict formatting
of the input and never 'close' the final </body> tag.
In order to fix that bad behaviour, we trigger the flushing of
remaining data on both </body> and </sami>.
Fixes #557365