[cairo] Testing legacy X servers in make check

[Behdad Esfahbod]

Hi,

I had to fix a bug in RHEL5 with cairo 1.2 failing to work with 15-bit
legacy X servers.  To reproduce the bug I found that this works:

  Xvfb -screen 0 650x480x15 :1 -pixdepths 15 -render

And a snapshot of the screen can be taken using:

  DISPLAY=:1 import -window root snapshot.png

Thought we may want to add targets to the test suite to test all depths
that we're supposed to support...

Anyway, something for ickle to consider :P, as well as documenting these
two commands in the archives.

Cheers,

-- 
behdad
http://behdad.org/

"Those who would give up Essential Liberty to purchase a little
 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759