obs-studio/libobs/util/simde

This is a slightly modified version of the simde directory in
https://github.com/simd-everywhere/simde/commit/c3d7abfaba6729a8b11d09a314b34a4db628911d

Modifications:
1. Unused files have removed.
2. The code was reformatted using the "formatcode.sh" script in the root of this repository.