make rpm has been broken in several kernel versions, fix it.  Solves
http://bugme.osdl.org/show_bug.cgi?id=373 which Paolo Ciarrocchi pushed
me to fix.

1) Moved make rpm to the noconfig section, thus allowing it to see
   the clean target.
2) Fixed the commandline for find
3) Use rpmbuild if present
4) In mkspec use the generic all target, and drop the dep target
   This made the build command arch independent