sys/conf/makeLINT.mk to only do certain things for certain
architectures.
Note that neither arm nor mips have the Makefile there, thus
essentially not (yet) supporting LINT. This would enable them
do add special treatment to sys/conf/makeLINT.mk as well chosing
one of the many configurations as LINT.
This is a hack of doing this and keeping it in a separate commit
will allow us to more easily identify and back it out.
Discussed on/with: arch, jhb (as part of the LINT-VIMAGE thread)
MFC after: 1 month
