ports/137373: x11/libX11: make dependance on x11/libxcb

[John Hein]

Carlos A. M. dos Santos wrote at 18:22 -0200 on Nov 17, 2009:
 > On Tue, Nov 17, 2009 at 3:07 PM, Robert Noland <rnoland at freebsd.org> wrote:
 > > There is a pretty fair risk of breaking several other ports with this.
 > > Other ports that also expect xcb to be present would need to be modified
 > > to either have xcb disabled or fail if libX11 does not have the needed
 > > functionality.
 > 
 > That's exactly why I made it optional, default on, keeping the
 > default behavior.

I think that what Robert may be saying is that even if it's default is
'on', people will turn it off, and we might see lots of questions
about why this port or that port isn't working.

Maybe you can investigate a few ports that may need the xcb-ness
of libX11 and see what it takes to make them work in an xcb-free
flavor of libX11 (or hint at build time that they won't work
if libX11 doesn't have xcb).

The alternative is to commit this change and just see what breaks.
But doing a little investigation ahead of time to give us a heads up
about what to expect would be useful.