[RFA] Use gdb::unique_xmalloc_ptr when calling tilde_expand

[Tom Tromey]

>>>>> "Simon" == Simon Marchi <simon.marchi@polymtl.ca> writes:

Simon> There is still a cleanup in reload_shared_libraries_1, so I don't
Simon> think the do_cleanups should be removed.

Ugh, sorry about that.

That code is duplicating the bfd's file name.  But I can't see why
that's important.  I think just removing the xstrdup and the
make_cleanup is the right thing to do here.  What do you think?

Tom