apetag: use int64_t for filesize

CC: libav-stable@libav.org
(cherry picked from commit e816aaacd68201b67182f9c70dc680e89a0123e9)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>
tiff: do not overread the source buffer

At least 2 bytes from the source are read every loop.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
(cherry picked from commit 9c2216976907336dfae0e8e38a4d70ca2465a92c)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

Conflicts:
	libavcodec/tiff.c