Revert "codecparsers: remove ignored increment of return"

Revert "codecparsers: remove ignored increment of return"

This reverts commit 916b954315abc2f94348ec0be3e116c19b080b54.

Clearly something else was intended, and it also makes
more sense to add the extra bit. The resync marker is
N zero bits plus a 1 bit, and the pattern/mask needs to
be run on N+1 bits too.

(Even after the rever the code doesn't do that of course, so
it still needs to be fixed differently.)

https://bugzilla.gnome.org/show_bug.cgi?id=739345