spirv-llvm-translator: build against llvm15
spirv-llvm-translator: build against llvm15

switch to the llvm 15 git branch

oscarfv/MINGW-packages,JPeterMugaas/MINGW-packages,oscarfv/MINGW-packages,stahta01/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,stahta01/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,oscarfv/MINGW-packages,lhmouse/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,JPeterMugaas/MINGW-packages