Any program that calls glXChooseVisual segfaults when using swrast.  This
obviously breaks every opengl-related program.  Backtrace and bisection
results follow.

FWIW, I'm running latest git everything with on an Intel G45.

Backtrace:

#0  0x00007ffff7838c5e in fbconfigs_compatible (a=0x7fffffffd0f0, 
    b=0x3d434d4554535953) at glxcmds.c:1230
#1  0x00007ffff7839acf in glXChooseVisual (dpy=0x603010, screen=0, 
    attribList=0x7fffffffd2e0) at glxcmds.c:1521
#2  0x0000000000400f16 in main (argc=1, argv=0x7fffffffd448) at twoctx.c:62

Bisection:

(Note: The skipped commit failed differently: programs complained about not finding an RGB GLX visual).

f972115d33e391499e049b83a1559959f2ca9f72 is the first bad commit
commit f972115d33e391499e049b83a1559959f2ca9f72
Author: Kristian Høgsberg <krh@bitplanet.net>
Date:   Mon Jul 19 14:57:59 2010 -0400

    glx: Add screen privates for dri drivers and moved some fields there
    
    GLXscreenConfigs is badly named and a dumping ground for a lot of stuff.
    This patch creates private screen structs for the dri drivers and moves
    some of their fields over there.

:040000 040000 3ae7b0621d90871d19ba4ce2c41720dfddfe10fe acce56f693cb384ed530edbb9c0525459386e2de M	src

git bisect start
# bad: [8122baf8badfa9fe7a80bfc904ad7b6ddcdecb0c] softpipe: Check for NULL pointer in sp_destroy_tile_cache().
git bisect bad 8122baf8badfa9fe7a80bfc904ad7b6ddcdecb0c
# bad: [c20a3628c7c6b7c41efe309b712bf93eb4e92039] glsl: remove invalid _mesa_problem() call
git bisect bad c20a3628c7c6b7c41efe309b712bf93eb4e92039
# bad: [600c85efdb0ff498c1f62e74efbda9f7096a74d3] Revert "dri2: Remove an unused variable."
git bisect bad 600c85efdb0ff498c1f62e74efbda9f7096a74d3
# good: [f9d11b8cee235dae42f757e21c2536391c07b3e8] i965: Mostly fix glsl-max-varyings.
git bisect good f9d11b8cee235dae42f757e21c2536391c07b3e8
# bad: [4363d4d0b945c4ca6c303fb337e1fac39e6e1ad6] gallivm: fix indirect addressing of constant buffer
git bisect bad 4363d4d0b945c4ca6c303fb337e1fac39e6e1ad6
# bad: [a7292f2920a28a190ca39ce530454a852ec36d59] glx: Move DRI CopySubBuffer extension to DRI1 code
git bisect bad a7292f2920a28a190ca39ce530454a852ec36d59
# skip: [089fc37c6fa158824279e08e3b378ced94d6f803] glx: Move DRI1 specific extensions and code to DRI1 screen private
git bisect skip 089fc37c6fa158824279e08e3b378ced94d6f803
# bad: [70887d517290060a80c7f5dd8c0ea0c834c4d91e] glx: Move __driScreen into the dri screen privates
git bisect bad 70887d517290060a80c7f5dd8c0ea0c834c4d91e
# bad: [f972115d33e391499e049b83a1559959f2ca9f72] glx: Add screen privates for dri drivers and moved some fields there
git bisect bad f972115d33e391499e049b83a1559959f2ca9f72
# good: [308e13ecd12a2fd894e5b509d5756bffc2035ec6] glx: Factor out common code from dri2WaitGL() and dri2WaitX()
git bisect good 308e13ecd12a2fd894e5b509d5756bffc2035ec6
# good: [a296d96de45d38a6ed0b3c817334d443facc169b] glx: Rename various DRI structs away from obnoxious __GLXfooRec convention
git bisect good a296d96de45d38a6ed0b3c817334d443facc169b