[Triple] Ignore the vendor field for MinGW, wrt LTO/IR compatibility (#122801)

For MinGW environments, the regular C/C++ toolchains usually use "w64"
for the vendor field in triples, while Rust toolchains usually use "pc"
in the vendor field.

The differences in the vendor field have no bearing on whether the IR is
compatible on this platform. (This probably goes for most other OSes as
well, but limiting the scope of the change to the specific case.)

Add a unit test for the isCompatibleWith, including some existing test
cases found in existing tests.

0 files changed, 0 insertions, 0 deletions