[libobjc] Shouldn't "version" take a long?

[Jose Quinteiro]

Hello,

The getter/setter for version in Object.M gets/takes an int, and they 
eventually get/set the "version" field in struct objc_class.   This 
field is declared as a long in objc/objc.h.

I'm asking because I think this was causing a crash in GNUMail on 64-bit 
systems.  More detail:

https://bugs.gentoo.org/show_bug.cgi?id=193806

Thanks,
Jose.