[Xcb] More x11perf port, new util/image

[Barton C Massey]

The good news: I got do_rect.c in x11perf ported---which
means that I got bitmaps.c ported, which means that I got
xcb_create_pixmap_from_bitmap_data() working.  So the rest
of the x11perf port should be "straightforward".

The bad news: I've essentially completely rewritten
util/image in the process.  Not much documentation for it
yet, which is too bad, since there are a number of issues to
bring up and discuss.  I'll try to post some stuff here
tomorrow and to bring the doxygen up to date, at the very
least.

The good news, again, is that the new code seems to work for
a variety of testcases, and looks (to its author :-) like a
robust and maintainable codebase that gets most of the
bizarre corner cases of X image right (or at least will when
the bugs I have yet to encounter have been removed---anyone
want to test deep xy-pixmap on a mixed-endian machine? :-).

As mentioned earlier, there's also a few enhancements to
util/convenient in my tree.

Hopefully folks will review my code and then help merge it
into the XCB util mainline for a new release.  I'm pretty
optimistic that it's headed in the right direction for this.

  git://people.freedesktop.org/~bart/git/util.git
  git://people.freedesktop.org/~bart/git/x11perf.git

Thanks hugely to Ian and Vincent for the original util/image
code, which was major help in getting the rewrite started.

    Bart