toolchain/52829: adjusting gdb tui window so it is too short segfaults

[coypu%sdf.org@localhost]

>Number:         52829
>Category:       toolchain
>Synopsis:       adjusting gdb tui window so it is too short segfaults
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Dec 16 22:50:00 +0000 2017
>Originator:     coypu
>Release:        NetBSD 8.0
>Organization:
>Environment:
NetBSD 8.0, gdb 7.12
>Description:

>How-To-Repeat:
gdb -q
C-x 2 (or 'tui enable')
keep resizing the terminal window so it is too short.

Core was generated by `gdb'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000071255c01ad33 in redrawwin () from /usr/lib/libcurses.so.7
(gdb) bt
#0  0x000071255c01ad33 in redrawwin () from /usr/lib/libcurses.so.7
#1  0x0000000104410c42 in tui_refresh_all ()
#2  0x000000010441293a in tui_refresh_all_win ()
#3  0x0000000104412d78 in ?? ()
#4  0x0000000104303761 in ?? ()
#5  0x0000000104304088 in start_event_loop ()
#6  0x0000000104288415 in ?? ()
#7  0x0000000104304cf5 in catch_errors ()
#8  0x00000001042895bb in gdb_main ()
#9  0x0000000104595660 in main ()
>Fix: