DVDCodecs: Amlogic: Handle conditions in which amcodec should be opened during Open()

DVDCodecs: Amlogic: Use mpeg2 video codec for mpeg2's

* AM Video Codec cannot properly handle the still-frames within DVDs

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>

DVDFactoryCodec: Remove throttling of mpeg2 to libmpeg2 for amlogic

* Thanks to @kszaq, am-mpeg2 can handle all mpeg2's however it can't handle the still frames (which is caught above it).
* Testing .VOB isn't setting hint.stills to true so will need to address this in separate patch

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>

DVDFactoryCodec: Further conditionalize HAS_LIBAMCODEC opening

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>

DVDFactoryCodec: Amlogic: Force rmvb to ffmpeg

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>

DVD: Amcodec: Handle conditions in which amcodec should be using during open

* Instead of before

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>
Merge pull request #4539 from Matricom/amcodec

DVDCodecs: Condense and update HAS_LIBAMCODEC
[depends] move ffmpeg to unified deps
[configure] remove internal ffmpeg
remove ffmpeg from tree
ffmpeg: remove dll wrappers
add ffmpeg lock manager
todo: refactor to own file
ffmpeg: move callbacks into separate file
remove ffmpeg dlls from generated headers
not removing win32 as this might still be needed?
[rpi] setup-sdk.sh: allow overriding of buildroot and xbmc install paths
also don't require root if not needed
add ffmpeg makefile for rpi
[WIN32] download and compile ffmpeg from remote source.
[WIN32] make XBMC compile, build and run with the ffmpeg link libraries.
[WIN32] use ffmpeg version from tools\depends\target\ffmpeg\FFMPEG-VERSION
[WIN32] prepare mingw build files for jenkins.
[WIN32] removed old mingw build files.
ffmpeg: bump version to 2.2
[depends] add --with-platform=raspberry-pi switch
ffmpeg: change depreciated functions avcodev_alloc/free_frame
ffmpeg: change depreciated attributes qscale, qstride