doxy: Document avlog

Provide some information for every function and add a group.
x86: xviddct: Employ more specific ifdefs

This avoids building mmxext and sse2 code when disabled by configure.
x86: fdct: Initialize optimized fdct implementations in the standard way
swscale: provide a default scaler if none is set

Lanczos for general case, sinc for upscaling, Gaussian for
downscaling. According to current literature these scalers
should be the best quality-wise algorithms for each case.

Inspired from a patch by wm4 <nfxjfg@googlemail.com>

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
x86: dsputil: Separate ff_add_hfyu_median_prediction_cmov from dsputil_mmx

The function does not depend on MMX and compilation without MMX enabled
fails if the function is compiled conditional on MMX availability.
oggparsevorbis: return meaningful errors

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Merge commit '4272bb6ef1533846a788c259cc498562d0704444'

* commit '4272bb6ef1533846a788c259cc498562d0704444':
  doxy: Document avlog

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '0b8b2ae5e93d616c2ece59f7175f483154cff918'

* commit '0b8b2ae5e93d616c2ece59f7175f483154cff918':
  x86: xviddct: Employ more specific ifdefs

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '258414d0771845d20f646ffe4d4e60f22fba217c'

* commit '258414d0771845d20f646ffe4d4e60f22fba217c':
  x86: fdct: Initialize optimized fdct implementations in the standard way

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '6b3ff6f91a535d6383f41ca7bdf760165dcb6015'

* commit '6b3ff6f91a535d6383f41ca7bdf760165dcb6015':
  swscale: provide a default scaler if none is set

Conflicts:
	libswscale/utils.c

The default is left at bicubic until someone has compared the scalers
properly speed and quality wise.

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '2ddb35b91131115c094d90e04031451023441b4d'

* commit '2ddb35b91131115c094d90e04031451023441b4d':
  x86: dsputil: Separate ff_add_hfyu_median_prediction_cmov from dsputil_mmx

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  oggparsevorbis: return meaningful errors

Conflicts:
	libavformat/oggparsevorbis.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/vf_scale: dont duplicate default.

use the defaults set by swscale

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