SRCS to teach make(1) that many .c sources are dependent on it.
This fixes parallel (-j) builds and makes it possible to build
individual .o files separately.
While here, removed PROG from CLEANFILES -- it's taken care of
already by bsd.prog.mk.
to acpidb. The same problem exists in iasl. Add JIT patching there
too.
Add a comment to both makefiles to increase the chance that both
kludges are removed when a real solution is committed.
