avformat/mxfenc: Only store user comment related tags when needed

Also support disabling them as they seem to cause problems to some
Users. They are also not allowed in IRT D-10 thus the default for
mxf_d10 is not to write them

This also decreases the filesize when no user comment are stored

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit d9726893f311b7bbbc9887db2c3ffbefaad78ca3)

Conflicts:

	libavformat/mxfenc.c

0 files changed, 0 insertions, 0 deletions