x264, libgmp and libgpg-error updates

The following projects have been updated:

• ffmpeg was updated to 4.3.r96746.
• x264 was updated to 0.159.r2991.
• libgmp was updated to 6.2.0.
• libgpg-error was updated to 1.37.

Any projects that have a dependency that was updated has also been updated to build with the latest versions of the new libraries as well.