This simplifies make logic/output
While here, remove bogus CFLAGS which look for headers in cddl/lib/libumem.
There aren't any source files there (just Makefiles)
MFC after: 1 month
Sponsored by: Dell EMC Isilon
This both avoids some dependencies on xinstall.host and allows
bootstrapping on older releases to work due to lack of at least 'install -l'
support.
Sponsored by: EMC / Isilon Storage Division
Off by default, build behaves normally.
WITH_META_MODE we get auto objdir creation, the ability to
start build from anywhere in the tree.
Still need to add real targets under targets/ to build packages.
Differential Revision: D2796
Reviewed by: brooks imp
