Use cmake to build. This is the favored method of building by upstream.
Consequences:
- Build lld again
- Build LLVMgold
- Enable sanitizers on non-musl platforms
- Remove llvm-doc (not built by cmake, quite useless)
- Use versioned binary names
- Could use ninja with make_cmd=ninja and configure -Gninja, but we
stick to make for now.
Also cleaned up and fixed remaining patches.
dffb85bee2