This avoids SIMD-optimized functions having to sign-extend their
line size argument manually to be able to do pointer arithmetic.
Also adjust parameter names to be "stride" everywhere.
* commit 'f46bb608d9d76c543e4929dc8cffe36b84bd789e':
dsputil: Split off pixel block routines into their own context
Conflicts:
configure
libavcodec/dsputil.c
libavcodec/mpegvideo_enc.c
libavcodec/pixblockdsp_template.c
libavcodec/x86/dsputilenc.asm
libavcodec/x86/dsputilenc_mmx.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>