(toplevel patch) Move gcc_version_trigger from configure to configure.in

[DJ Delorie]

> After fiddling around, I concluded this one was best submitted as is,
> so here it is: outstanding patch #3, after de-vault and dependency tidy.
> 
> Needed before I can get host subdir configuration into the Makefile.
> Tested on i686-pc-linux-gnu.
> 
> 	* configure: Move gcc_version_trigger stuff from here...
> 	* configure.in: ...to here.

Ok.