avcodec/x86/hevc_deblock: add %ifs to avoid "do nothing instructions"

cherry picked from commit f7843356253459e6010320292dbbc1e888a5249b
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/x86/hevc_deblock: use of paddw instead of psllw

cherry picked from commit f7843356253459e6010320292dbbc1e888a5249b
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/x86/hevc_deblock: use test instead of cmp 0

cherry picked from commit f7843356253459e6010320292dbbc1e888a5249b
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
hevc: cleanups in SSE2 and SSSE3 loop filters, use fewer instructions

cherry picked from commit f7843356253459e6010320292dbbc1e888a5249b
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/x86/hevc_deblock: cosmetics

cherry picked from commit f7843356253459e6010320292dbbc1e888a5249b
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>