mscoree: Better support RUNTIME_INFO_UPGRADE_VERSION in, GetRequestedRuntimeInfo (try 2)

[Vincent Povirk]

I suspect that RUNTIME_INFO_UPGRADE_VERSION will actually use the
newest non-4.0 version when it doesn't find an exact match, which is
why I asked you to add that test. I'm not sure whether Marvin's
results prove that or not.

If that's the case, get_runtime_info should probably be checking the
result of CLRMetaHost_GetRuntime, and proceeding to the
RUNTIME_INFO_UPGRADE_VERSION check if it fails.