Log message:
Simply and speed up buildlink3.mk files and processing.
This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.

Log message:
Merge cube-native-xorg, so that pkgsrc-current can be used with the native
X.Org found in NetBSD-current.

Thanks a lot to all who helped, especially Matthias Scheler who did
repeated tests on Mac OS X and older versions of NetBSD to make sure the
support for those platforms wouldn't be broken (or at least, not fatally,
as I would still expect a few hiccups here and there, because there is
only so much one can test in such limited time).

On the infrastructure side, this branch brings pkgconfig-builtin.mk, in
order to write very easily new builtin.mk files.  It can actually handle
more than just pkgconfig files, but it will provide a version if it finds
such a file.  x11.builtin.mk has also been made more useful and now all
existing (and future!) native-X11-related builtin.mk files should include
it.

Log message:
Fix my previous commit, which was borked in some cases. Noted by gson@.

Log message:
Update these for consistency (libXfixes/DESCR is related but didn't
need updating) and document which are the native-x11 and which are the
modular X.org versions.

Log message:
Make these fail with a comprehensible error message when X11_TYPE != native.

Log message:
Unbreak build of a lot of X11 packages on systems which use native X11
(e.g. NetBSD with bundled XFree86). Checking whether "X11_TYPE" is \ 
"xorg"
is obsolete and *not* equivalent to checking whether we are not using
modular X.org.

Log message:
Since X11_TYPE cannot be "xorg", there's no point in checking for that
condition. What was really meant is X11_TYPE != "modular".

Log message:
Whitespace cleanup, courtesy of pkglint.
Patch provided by Sergey Svishchev in private mail.

Log message:
Replace mk/bsd.prefs.mk includes with bsd.fast.prefs.mk includes.
The redundant parsing of bsd.prefs.mk is mostly avoided now and
parse time e.g. for x11/kdebase3 gets reduced by up to 10%.

Log message:
Conflict with libXfixes (currently in pkgsrc-wip).

This version of Xfixes is not supported and I have been using
the maintained version since last year on several pkgsrc build
systems. But I will not switch to new version until okayed by others.