Like MirrorOnceBorder, this requires the GL_EXT_texture_mirror_clamp extension. This extension is unfortunately not available on Intel's drivers (both Windows proprietary and Linux Mesa). Use GL_MIRROR_CLAMP_TO_EDGE as a fallback if the extension is unavailable.

Macro code is just uploaded sequentially from a starting address, however that does not mean the entry point for the macro is at that address. This PR adds preliminary support for executing macros in the middle of our cached code.

Add 32 bit component sizes to (un)signed scaled formats and group (un)signed normalized, scaled, and integer formats together.

General: Tune the priority of main emulation threads so they have higher priority than less important helper threads.