[Module::Build] Build clean demands re-run

[<and...@fr...>]

This is certainly a low priority job, but one might still think about
it:

 % ./Build clean                          
 * ERROR: Configuration was initially created with Module::Build version '0.2611',
   but we are now using version '0.2707'.  Please re-run the Build.PL or Makefile.PL script.

Maybe the clean target can be exempted from this re-run eagerness?

-- 
andreas