[MinGW] Treat any -lucrt* as replacing -lmsvcrt

Since SVN r314138, we check if the user has specified any particular
alternative msvcrt/ucrt version, and skip the default -lmsvcrt
in those cases.

In addition to the existing names checked, we should also treat
a plain -lucrt in the same way, mingw-w64 has now added a separate
import library named libucrt.a, in addition to libucrtbase.a.

Differential Revision: https://reviews.llvm.org/D49054

llvm-svn: 336654