Make openh264 built via vcpkg or cmake on Osx

[suhasHere]

The vpckg port for openh264 seems to be lacking assembly optimizations. Hence the current setup uses prebuilt osx binaries for the same.

This makes it not so useful as a long term solution.

[paulej]

vcpkg just pulls the source code. Rich is the one who created this vcpkg addition. So, if there is something more we need to do, he might be able to assist. I noted when I built this on Linux, I had to install nasm. Between Rich and changes to OpenH264's repo itself, I think we should be able to get this built with optimization.