HELP_FILES is a loader only thing, so move it to loader.mk. Only
generate the help file if HELP_FILES is defined. Adjust Makefiles to
new convention. Fix a few cases where ${.CURDIR}/ was missing
resulting in missing bits from the help files.
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Building with the standard system headers isn't a perfect match to the
stand environment. Instead, copy over the files we know are safe to
use and constrain what else is used. We use -nostdinc to achieve this.
This also fixes issues with building 32-bit libraries on amd64
sometimes pulling in the wrong cpufunc.h giving an error now that we
stop on errors. It will also enable an easier transition to lua boot.
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Default WARNS to 0 still, since there's still some warnings on other
architectures.
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Differential Revision: https://reviews.freebsd.org/D13301
Only define the CFLAGS we need.
SSP_CFLAGS is now defined globally, no need to define it here.
Define -D_STANDALONE globally for src/stand builds.
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Move kernel includes and libsa includes together at the top of defs.mk
Move all machine specific defines from Makefile.inc to their friends
in defs.mk.
Add comments and remove now useless junk after the move.
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