Merge swscale bloatup

This will be cleaned up in the next merge

Authorship / merged commits:
commit f668afd4
Author: Janne Grunau <janne-libav@jannau.net>
Date:   Fri Apr 15 09:12:34 2011 +0200

    swscale: fix "ISO C90 forbids mixed declarations and code" warning

    only hit with --enable-runtime-cpudetect

commit 7f2ae5c7
Author: Janne Grunau <janne-libav@jannau.net>
Date:   Fri Apr 15 02:09:44 2011 +0200

    swscale: fix compilation with --enable-runtime-cpudetect

commit b6cad3df
Author: Janne Grunau <janne-libav@jannau.net>
Date:   Fri Apr 15 00:31:04 2011 +0200

    swscale: correct include path to fix ppc altivec build

commit 6216fc70
Author: Luca Barbato <lu_zero@gentoo.org>
Date:   Thu Apr 14 22:03:45 2011 +0200

    swscale: simplify rgb2rgb templating

    MMX is always built. Drop the ifdefs

commit 33a0421b
Author: Josh Allmann <joshua.allmann@gmail.com>
Date:   Wed Apr 13 20:57:32 2011 +0200

    swscale: simplify initialization code

    Simplify the fallthrough case when no accelerated functions
    can be initialized.

commit 735bf195
Author: Josh Allmann <joshua.allmann@gmail.com>
Date:   Wed Apr 13 20:57:31 2011 +0200

    swscale: further cleanup swscale.c

    Move x86-specific constants out of swscale.c

commit 86330b4c
Author: Luca Barbato <lu_zero@gentoo.org>
Date:   Wed Apr 13 20:57:30 2011 +0200

    swscale: partially move the arch specific code left

    PPC and x86 code is split off from swscale_template.c. Lots of code is
    still duplicated and should be removed later.

    Again uniformize the init system to be more similar to the dsputil one.

    Unset h*scale_fast in the x86 init in order to make the output
    consistent with the previous status. Thanks to Josh for spotting it.

commit c0038328
Author: Luca Barbato <lu_zero@gentoo.org>
Date:   Wed Apr 13 20:57:29 2011 +0200

    swscale: move away x86 specific code from rgb2rgb

    Keep only the plain C code in the main rgb2rgb.c and move the x86
    specific optimizations to x86/rgb2rgb.c
    Change the initialization pattern a little so some of it can be
    factorized to behave more like dsputils.

Conflicts:
	libswscale/rgb2rgb.c
	libswscale/swscale_template.c