[LLVM->SPIRV] Translate `AddrSpaceCast from generic null` to OpGenericCastToPtr#3411

wenju-he wants to merge 3 commits intoKhronosGroup:mainKhronosGroup/SPIRV-LLVM-Translator:mainfrom

wenju-he:AddrSpaceCastInst-ConstantPointerNull-SrcAddrSpace-SPIRAS_Genericwenju-he/SPIRV-LLVM-Translator:AddrSpaceCastInst-ConstantPointerNull-SrcAddrSpace-SPIRAS_GenericCopy head branch name to clipboard