K 10
svn:author
V 6
brooks
K 8
svn:date
V 27
2019-10-15T21:27:06.855606Z
K 7
svn:log
V 716
Add the ability to link programs against a compat ABI.

Linkage is controlled by two make knobs:
	WANT_COMPAT - Prefer to link against the compat ABI.
	NEED_COMPAT - Link against the compat ABI or fail to build.

Supported values are "32", "soft", and "any".  The latter meaning pick
the first[0] supported compat ABI.

This can be used to provide test binaries for compat ABIs or to link
ABI-specific programs.

[0] We currently support only one compat ABI at a time, but this may
change in the future and some code in this commit is structured to ease
that change.

Reviewed by:	bdrewery, jhb
Obtained from:	CheriBSD (in concept)
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D22023

END