mips-sgi-irix6-gdb (5.3 branch and mainline) failed to link on
athlon-pc-linux-gnu.  breakpoint.c didn't to compile in
disable_breakpoints_in_shlibs() because SOLIB_ADD was not defined.  I
think solib.h must be #included somewhere, and I think the right place
is config/mips/tm-irix6.h.  I couldn't test this natively, because I
don't have access to any irix box at the moment, but the cross
debugger built correctly with this patch.  Ok to install?