avcodec/hevc: fix chroma transform_add size

Fixes accessing misaligned address
Fixes: signal_sigsegv_1feb99c_10_signal_sigsegv_2d1d35c_79_cov_691940146_EXT_A_ericsson_3.bit

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: reuse edge emu buffer for coefficients

Kind of hackish but...

Reviewed-by: Mickael Raulet <Mickael.Raulet@insa-rennes.fr>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: remove CodingTree

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: remove unneeded buffer.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: move intermediate bidir buffer

Other buffers are already there.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Conflicts:
	libavcodec/hevc.c