Provide quartz-only variant of cairo port

[macports@…]

The cairo port currently provides three variants: universal, which builds all of cairo's backends (e.g., freetype and quartz on Mac OS X); glitz, which (in addition) enables glitz and no_x11, which disables X11 functionality.

I would like to see a pure quartz variant. It is desirable to have only one font subsystem (quartz). This is not yet generally feasible because many applications do not support the quartz back-end. However, a pure quartz variant would allow developers to easily build an environment from which they could continue to port applications to support the quartz back-end. Broken, for lack of a better word, applications would immediately reveal themselves as they would not build and/or execute.

If a user is only interested in a subset of applications that do support the quartz back-end, then he may install them without many unnecessary dependencies.

Of course, the universal build should remain the default for quite some time (if not forever).

This was discussed in ticket #15052. I opened a separate ticket so that it may be tracked.

[jmr@…]

Assigning to maintainer.

[ryandesign@…]

I wonder if we can roll this into the no_x11 variant. Or are there any cases where one would want the fontconfig backend but not the xlib backend? Hmm.

FYI: The universal variant is not on by default and it has nothing to do with what cairo backends are enabled; see the FAQ.