Third-party notices for the pinned ReXGlue runtime and PSU GPU plugin.

The following source revisions and license texts accompany this prerelease:
sdl3-LICENSE.txt.txt - https://github.com/libsdl-org/SDL/tree/147a8ee32dbf9ac02f3794964490687b6bbda1bc
fmt-LICENSE.txt - https://github.com/fmtlib/fmt/tree/407c905e45ad75fc29bf0f9bb7c5c2fd3475976f
spdlog-LICENSE.txt - https://github.com/gabime/spdlog/tree/79524ddd08a4ec981b7fea76afd08ee05f83755d
xxHash-LICENSE.txt - https://github.com/Cyan4973/xxHash/tree/e626a72bc2321cd320e953a0ccf1584cad60f363
imgui-LICENSE.txt.txt - https://github.com/ocornut/imgui/tree/6d910d5487d11ca567b61c7824b0c78c569d62f0
simde-COPYING.txt - https://github.com/simd-everywhere/simde/tree/71fd833d9666141edcd1d3c109a80e228303d8d7
tomlplusplus-LICENSE.txt - https://github.com/marzer/tomlplusplus/tree/30172438cee64926dc41fdd9c11fb3ba5b2ba9de
utfcpp-LICENSE.txt - https://github.com/nemtrif/utfcpp/tree/63d64de49fd6b829f7c8694df5ab2ee625cb7134
o1heap-LICENSE.txt - https://github.com/pavel-kirienko/o1heap/tree/388a73fd9007300e5130c5fe352d9ce3288b6dde
cli11-LICENSE.txt - https://github.com/CLIUtils/CLI11/tree/bfffd37e1f804ca4fae1caae106935791696b6a9
libmspack-COPYING.LIB.txt - https://github.com/kyz/libmspack/tree/305907723a4e7ab2018e58040059ffb5e77db837
FFmpeg-COPYING.LGPLv2.1.txt - https://github.com/wmarti/FFmpeg/tree/0604b464c7cb4ebc94940cf1f324a3b26b87717c
FFmpeg-LICENSE.md.txt - https://github.com/wmarti/FFmpeg/tree/0604b464c7cb4ebc94940cf1f324a3b26b87717c

FFmpeg/libmspack are linked into rexruntime.dll by the pinned SDK. Their corresponding source and build configuration are available from the pinned source revisions above and the ReXGlue source tree. The project source snapshot includes the PSU GPU patch and build scripts.

ReXGlue source and submodules: https://github.com/rexglue/rexglue-sdk/tree/bd833a2ab69d305f99ddf57418fc38ffec8af93d
