lld-link: Add --rsp-quoting= flag.

This ports https://reviews.llvm.org/D19425 from clang /
https://reviews.llvm.org/D22015 from the ELF port to COFF lld. This can be
useful when linking COFF files on a posix host.

https://reviews.llvm.org/D37452

llvm-svn: 312594