[settings] Only need a confirmation dialogue when resolution has changed

This fixes a bug when every time video output settings page is opened it asks if you would like to keep this change
Merge pull request #4498 from popcornmix/reschange

[settings] Only need a confirmation dialogue when resolution has changed
[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?
sq to configure - add --with-ffmpeg=force option
this will always build our ffmpeg version, even if its found in system
only enable auto building ffmpeg if we are not cross compiling
[rpi] setup-sdk.sh: allow overriding of buildroot and xbmc install paths
also don't require root if not needed
sq to configure - fixup after upstream rebase
add ffmpeg makefile for rpi
sq to configure - unset PKG_CONFIG_SYSROOT_DIR when getting FFMPEG_LIBDIR
sq to setup-sdk.sh - fix sudo needs detection
bump ffmpeg
sq to depends - add a single file to specify our ffmpeg version
sq to rpi ffmpeg makefile - use FFMPEG-VERSION file
sq to configure - use FFMPEG-VERSION file in autobuild.sh