All the NO_foo options processed in src.opts.mk are really bsd.opts.mk
options, so move their processing there. This fixes issues with
Makefiles that define NO_MAN=t and only inlcude bsd.*.mk files. A few
ports fell into this category, and they should be fixed by this change.
Also, for now, disable the warning about NO_foo being deprecated. More
work is needed than anticipated before we can do that, so kill the
noise for now.
bsd.compiler.mk was implicitly included by bsd.own.mk in historical
versions. With its movement to src.opts.mk, bsd.prog.mk was testing
COMPILER_TYPE without including the bsd.compiler.mk anymore. In the
source tree, this caused no problems, for reasons that aren't clear,
but does cause problems outside of the source tree. Allow
bsd.compiler.mk to be included multiple times safely, and always
include bsd.compiler.mk at the top of bsd.prog.mk. Resist the urge to
put it in bsd.init.mk, since that would reintroduce the implicit
include.