[RFC]: m4 update

hi

I made a patch that updates our in-tree m4 to the version from OpenBSD.
Their version contains some gnu extensions and generally is modernized
and rewritten.

The patch (you have to in src/usr.bin/m4 for it to apply):


	http://vlakno.cz/~rdivacky/m4.patch


I added their ohash* implementation to the m4 subdir as it uses it. I
am not sure this is the correct way but it works for now. 

So the question is - do we want this at all? If so, is this the way we 
want it?

I am open to all comments, thank you!

roman