Ignore import warnings from ffmpeg.

Seems to be a known issue with the msvc ffmpeg stuff.
Fix some arm emitter warnings on win64.

We link it in for debugging purposes.
Align the GPU so the tick count can be aligned.

It's atomic for free on 64 bit, but only if it's aligned.
Assert some unlikely buffer overflows.
Avoid some unlikely uninitialized values.
Fix a small type comparison warning.
Merge pull request #4329 from unknownbrackets/warnings

Warning fixes