${BUILDLINK_DIR}. The consensus on tech-pkg@netbsd.org (2000-09-10)
seems to be to fix the packages that include <GL/xmesa.h> instead of
using a workaround.
already exist. This file is in Mesa-3.4.2, but not in the Mesa included
with XFree86-4.x where the definitions in the file have migrated elsewhere.
We create an empty one in this case to prevent compile errors caused by
source files including xmesa.h and not finding it.
linked from a particular package, and add a pre-configure target to
the buildlink.mk file to more painlessly use buildlink.mk files. A
${BUILDLINK_TARGETS} variable still exists in case a package _must_
define NO_CONFIGURE.
