[PATCH][gdb/testsuite] Don't leak tuiterm.exp spawn override

[Tom Tromey]

>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:

Tom> This fix uses a load_lib override.

Tom> Any comments?

There was a report recently about gdb overrides like this breaking
with a newer dejagnu.

Maybe we need a gdb_load or something like that, instead of
monkey-patching dejagnu?  Or some other different approach.

I'm not really opposed to this FWIW.  It seems not likely to cause
problems.  Though I thought that about the other override too, so..

Tom