dsputil: Split off pixel block routines into their own context
avformat/hlsenc: correctly compute target duration

With HLS, the duration of all segments must be lower or equal to the target
duration. Therefore floor(duration + 0.5) yields incorrect results.

For example, for duration = 1.35, floor(duration + 0.5) yields 1.0, but the
correct result is 2.0.

Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
Merge commit 'f46bb608d9d76c543e4929dc8cffe36b84bd789e'

* 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>
configure: add new dependencies for spp & mpdecimate

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