arm: Don't clobber callee saved registers in scalarproduct

q4-q7/d8-d15 are supposed to not be clobbered by the callee.

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit d307e408d4a9ada22df443cc38be77cc5e492694)
VC1: Fix intensity compensation performance regression

Fix https://trac.ffmpeg.org/ticket/3204

The problem was that intensity compensation was always used once it was
encountered. This is because v->next_use_ic was never set back to zero.
To fix this, when resetting v->next_luty/uv, also reset v->next_use_ic.

This improved (restored) performance by 85% when decoding
http://bit.ly/bbbwmv

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit ed5bed4152203aed8cce01a679bed67bbda8903f)