Pull up following revision(s) (requested by dsainty in ticket #960):
	lib/libcurses/setterm.c: revision 1.51
Fix a NULL dereference if the exit_alt_charset_mode capability is not
defined.
The previous version of this file changed a terminal initialisation test on
the exit_attribute_mode capability, checking for the exit_alt_charset_mode
capability as a substring, rather than performing a search for the
hard-coded
^O character.
That works better on terminals where ^O is not the correct value for
exit_alt_charset_mode.  But it works worse on terminals that don't have a
definition specified for exit_alt_charset_mode.
For example:
% TERMCAP='xterm:me=\E[m:' TERM=xterm vi
segmentation fault (core dumped)  TERMCAP='xterm:me=\E[m:' TERM=xterm vi
The crash can be avoided (without fixing the bug) by defining
exit_alt_charset_mode:
% TERMCAP='xterm|:me=\E[m:ae=:' TERM=xterm vi
ex/vi: Error: xterm: No such process
We now test exit_alt_charset_mode for NULL before continuing with the fatal
test, restoring the original no-crash behaviour.
XXX does_ctrl_o() is now just a naive reimplementation of strstr(), so
should
probably just use strstr() instead.
Ticket 960