avcodec/tiff: reset geotag_count in free_geotags()

Fixes null pointer dereference
Fixes: signal_sigsegv_19d922e_3688_cov_1577641655_aletrek_tiff.mov
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/hevc: propagate error code from hls_coding_quadtree()

Fixes use of uninitialized memory
Fixes out of array read
Fixes: asan_static-oob_123cee5_2630_cov_1869071233_PICSIZE_A_Bossen_1.bin
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>