(whether 2.0 or 1.2-compatible) into one file, motif.buildlink.mk.
lesstif12/buildlink.mk now assumes that if you include it, then you
actually want lesstif12.
To select that you want a Motif-1.2-compatible installation, define
USE_MOTIF12 in the package Makefile. If MOTIF12BASE is also defined, then
assume it points to a valid Motif-1.2 installation. Otherwise, auto-detect
whether /usr/dt is valid, or if we need lesstif12.
BUILDLINK_PREFIX.<pkgname>. This allows buildlink to find X11BASE packages
regardless of whether they were installed before or after xpkgwedge was
installed. Idea by Alistair Crooks <agc@pkgsrc.org>.