Clang 10 ci build added.
Clang 10 ci build added.

offa/seasocks,mattgodbolt/seasocks,mattgodbolt/seasocks,mattgodbolt/seasocks,offa/seasocks,offa/seasocks,mattgodbolt/seasocks,offa/seasocks,offa/seasocks,mattgodbolt/seasocks,offa/seasocks,mattgodbolt/seasocks