Re: [PATCH] mfplat: Don't unregister MFTs when registering with empty factories.

[Nikolay Sivov]

This will need more tests, as far as I can tell MFTRegisterLocal(NULL) 
does unregister, and following MFTUnregisterLocal() return ERROR_NOT_FOUND.

Interesting cases to cover are:

- is MFTRegisterLocal(NULL) an equivalent of MFTUnregisterLocal(NULL) or 
MFTUnregisterLocal(NULL) + MFTUnregisterLocalCLSID(NULL);
- same as above but for MFTRegisterLocalCLSID(NULL);
- is MFTUnregisterLocal(NULL) the same as MFTUnregisterLocalCLSID(NULL).