gdb crashes on current

[Vitaly Shevtsov <shev.vt1984%gmail.com@localhost>]

Hello!

It seems that gdb from base NetBSD image doesn't work with netbsd's
libcurses in tui mode:

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000756547929fba in _lwp_kill () from /usr/lib/libc.so.12
[Current thread is 1 (process 12621)]
(gdb) bt
#0  0x0000756547929fba in _lwp_kill () from /usr/lib/libc.so.12
#1  0x000000000101ef97 in handle_fatal_signal(int) ()
#2  0x000000000101f152 in handle_sigsegv(int) ()
#3  <signal handler called>
#4  0x0000756547e679e1 in prefresh () from /usr/lib/libcurses.so.9
#5  0x0000000000eec1a0 in tui_source_window_base::refresh_window() ()
#6  0x0000000000eedf18 in tui_unhighlight_win(tui_win_info*) ()
#7  0x0000000000eec5f8 in
tui_source_window_base::do_erase_source_content(char const*) ()
#8  0x0000000000ef60e5 in tui_layout_split::apply(int, int, int, int, bool) ()
#9  0x0000000000ef4aa8 in tui_apply_current_layout(bool) ()
#10 0x0000000000ef4ddb in tui_set_layout(tui_layout_split*) ()
#11 0x0000000000ee4f2f in tui_enable() ()
#12 0x0000000000ee5487 in tui_rl_switch_mode(int, int) ()
#13 0x0000000001379fa8 in _rl_dispatch_subseq ()
#14 0x000000000137aa27 in _rl_dispatch_callback ()
#15 0x000000000135a1f1 in rl_callback_read_char ()
#16 0x000000000101f40e in gdb_rl_callback_read_char_wrapper_noexcept() ()
#17 0x000000000102020d in gdb_rl_callback_read_char_wrapper(void*) ()
#18 0x000000000101eeb1 in stdin_event_handler(int, void*) ()
#19 0x0000000001300eba in gdb_wait_for_event(int) [clone .part.0] ()
#20 0x000000000130155a in gdb_do_one_event(int) ()
#21 0x0000000000fa0576 in captured_command_loop() ()
#22 0x0000000000fa2113 in gdb_main(captured_main_args*) ()
#23 0x00000000013c66fb in main ()