[compiler-rt] [test] [builtins] Pass the right parameters for linking with...

[compiler-rt] [test] [builtins] Pass the right parameters for linking with -nodefaultlibs on mingw targets

The clang-cl/MSVC case is handled above, thus consider win32 && !is_msvc
to be mingw.

This matches the list of libraries passed by e.g. the libcxx build, when
using -nodefaultlibs.

Differential Revision: https://reviews.llvm.org/D147647