gdb index feature

[Tom Tromey]

We're going to be pushing in a new gdb feature that creates indices for
the debuginfo.  These indices are created by gdb, then merged into the
executable or shared library using objcopy.  This will be done as part
of the find-debuginfo.sh script, run by RPM.  The point of this change
is that it greatly speeds up gdb startup.  It also greatly reduces gdb
memory use.

I am not completely sure when all the work will appear in rawhide, but I
wanted to send a short warning in case something is broken.  If this
process causes some problem, please report it against "gdb" in bugzilla,
and somebody will look at it ASAP.

thanks,
Tom