how to use MKDEBUGLIB=yes with gdb ?

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

Hello,
I've compiled a netbsd-7 release with MKDEBUGLIB=YES MKDEBUG=YES and
extracted the debug and xdebug sets. gdb finds the debug information
for the binary, but not for the dynamic libraries:
comore:/home/bouyer>gdb /usr/X11R7/bin/glxgears
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Reading symbols from /usr/X11R7/bin/glxgears...Reading symbols from /usr/libdata/debug//usr/X11R7/bin/glxgears.debug...done.
done.
(gdb) run
Starting program: /usr/X11R7/bin/glxgears 

Program received signal SIGSEGV, Segmentation fault.
[Switching to LWP 1]
0xbbbbdf00 in glLightfv () from /usr/X11R7/lib/libGL.so.2
(gdb) where
#0  0xbbbbdf00 in glLightfv () from /usr/X11R7/lib/libGL.so.2
#1  0x0804ac34 in init ()
    at /dsk/l1/misc/bouyer/netbsd-7/src/../xsrc/external/mit/mesa-demos/dist/src/xdemos/glxgears.c:398
#2  main (argc=1, argv=0xbfbfec28)
    at /dsk/l1/misc/bouyer/netbsd-7/src/../xsrc/external/mit/mesa-demos/dist/src/xdemos/glxgears.c:790


How can I tell gdb to use /usr/libdata/debug/usr/X11R7/lib/libGL.so.2.0.debug
to get extra informations ? I tried a few things but none did work
as expected.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--