comctl32: move up-down msg seq tests into new 'msg' test

[Felix Nawothnig]

James Hawkins wrote:
> This is not what needs to happen.  The generic message sequence
> testing code needs to be factored into msg.c, but the specific tests
> need to stay in each control's test file.

Guessed so... How about putting it into include/wine/test.h to share the 
code with user32/msg? Wouldn't help object size but I don't think a 
shared lib would be worth it...

Felix