Revert "ffmpeg: fixup compile error in patch"

This reverts commit fcbc5e9a2a320c0b3bb6d6555143e863f1db3158.
Revert "vaapi: don't unmap non-existing buffer"

This reverts commit c1597430e6d2dfd6b644be0345e0df9e0fe44336.
Revert "ffmpeg: add patch file for vaapi fix"

This reverts commit 4f47cfc9726c46ee69c72bdc4a28c15f1caea342.
[ffmpeg] - backport fix for crashing when using vaapi (found on libav mailing list) - this was signed off by elupus