[patch] Fix crash on NULL rl_prompt

[Tom Tromey]

>>>>> "Jan" == Jan Kratochvil <jan.kratochvil@redhat.com> writes:

Jan> BTW don't you think xstrdup (NULL) should == NULL?  Like xmalloc
Jan> (0) == NULL.

I personally don't care either way.  If you want to do it, that is fine
by me.

Jan> 2010-03-30  Jan Kratochvil  <jan.kratochvil@redhat.com>
Jan> 	* tui/tui-io.c (tui_prep_terminal): Permit NULL rl_prompt.

Ok.

Tom