Add the /nologo flag to llvm-ml

This flag is present in MSVC's ml.exe to suppress copyright info output.
LLVM doesn't output copyright info, so this flag does nothing in
llvm-ml. We still add this flag though so that when llvm-ml is used as a
drop-in replacement for MSVC ml.exe, we don't get any extra warnings.
Furthermore, this behavior is also consistent with other llvm binaries
for Windows (e.g. clang-cl, llvm-mt, lld-link, etc.)

Differential revision: https://reviews.llvm.org/D123068