Changes of note:
Added target-flags.mk allows frobbing CFLAGS for individual
targets.
prog.mk and lib.mk attempt to use bsd.prog.mk and bsd.lib.mk
to help ensure the right magic happens on ELF systems.
Several improvments to autodep.mk - now the default unless
NO_AUTODEP is defined.
The bsd.*.mk files are no longer installed on BSD systems as they are
almost guaranteed to do more harm than good.
Reviewed: agc
