Nettle, GnuTLS, x264 updates

The following projects have been updated:

• ffmpeg was updated to 4.5.r102797.
• Nettle was updated to 3.7.3.
• GnuTLS was updated to 3.7.2.
• x264 was updated to 0.163.r3065.

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.