Add check to SetMenuItemInfo

[Alistair Leslie]

> I'm not opposed to your fix, not at all. I just would like to understand
> better what is the real problem with our code. If you, or somebody else,
> could confirm (by a test case) that exactly (MFT_BITMAP | MFT_SEPARATOR)
> combination should be rejected then I'll vote for your patch.

Reading about the MENUITEMINFO structure.
Take from MSDN
The MFT_BITMAP, MFT_SEPARATOR, and MFT_STRING values cannot be combined with
one another.

Hope this helps
Alistair