libvlccore: Rename iso_lang.h to vlc_iso_lang.h because we use VLC_EXPORT there, and plugins may use it.

Remove workarounds for broken (probably very old) FFmpeg .pc files
Errors out if nor swscale headers, nor img_resample() in libavcodec are
present

If stats are too heavy weight to use w/o debug, we should either fix
them or remove them completely anyway

Fix the rawvideo codec when visible_pitch != pitch. (And simplify code) This should fix partial screen captures using non multiple of 16 values.

Add some missing symbols in a blind attempt to fix the buildbots. Feel free to revert if this is wrong.

This is the last fix for libvlc.dylib compilation on Mac OS X.

This reverts commit 96cc9c26.

This commit is reverted because we are using a regexp to determine the list of exported symbols in libvlc. However some private symbols start with libvlc_, this produces (here on Mac OS X) a nmedit error about symbols not being found while exported. A solution is to externalize those private symbols, hence using VLC_PUBLIC_API.

Feel free to come up with a better solution.