Proper way to operate a git build and a regular package-manager installed X at the same time

[Joel Feiner]

I have (finally!) managed to get a git-based xorg tree built on my
Gentoo test install.  I have it live in /usr/local/xorg.  So far, things
seem to work mostly correctly, but some non-git programs seem to be
failing because -- I believe -- they aren't using the right libraries.
Now, I've set LD_LIBRARY_PATH to /usr/local/xorg/lib and that works for
some things.  But I seem to be having problems getting DRI to work
again, which is strange because it did work at one time with this git
build and now it's not.

glxinfo reports that direct rendering is unavailable.  Setting
LIBGL_DEBUG=verbose and running again reveals:

libGL: XF86DRIGetClientDriverName: 5.3.0 r300 (screen 0)
libGL: OpenDriver: trying /usr/lib/dri/r300_dri.so
libGL error: driver exports no extensions (/usr/lib/dri/r300_dri.so: 
undefined
symbol: __driDriverExtensions)
libGL: OpenDriver: trying /usr/lib/dri/swrast_dri.so
libGL error: dlopen /usr/lib/dri/swrast_dri.so failed
(/usr/lib/dri/swrast_dri.so: cannot open shared object file: No such file or
directory)
libGL error: unable to load driver: swrast_dri.so
libGL error: reverting to indirect rendering

ldd `which glxinfo` shows, however, that it's using all the right 
libraries.  So I'm not sure what's going on.  There's nothing at all in 
Xorg.0.log that indicates any error with DRM.  Everything looks normal 
and clean.  Also, EXA is still fast, which isn't true if DRI really 
isn't working.

So I don't know if this really isn't working because of a bug or 
regression, or if it's because my setup is messed up.  Any ideas?