ef4cfd8322
This precomputes some hashes that LLD uses for type merging to speed up linking when PDBs are enabled. Only do this if any kind of /DEBUG flag is passed to the linker. -gcodeview-ghash is orthogonal to /Z7, -g, -g1, or -gmlt, so it is safe to set it independently from those flags. It will not increase debug info emission. Differential Revision: https://reviews.llvm.org/D103287
See docs/CMake.html for instructions on how to build LLVM with CMake.