We received a report from someone whose build was failing because
of the use of cchar_t and setcchar(). They were getting errors
even though they were using an up-to-date curses library.
Apparently, ncurses requires that _XOPEN_SOURCE_EXTENDED must be
defined before the curses header files in order for those features
to be available.
We had already updated our .370 series of hints and hints/include
files with
-D_XOPEN_SOURCE_EXTENDED=1
but this person must have been building in some other way.
Instead of failing to build in that situation, allow the
fallback to the older, less-functional genl_putmixed() function,
but also try not to do so silently and display a message that
functionality is reduced.
The difference between the use of genl_putmixed() and
curses_putmixed() or tty_putmixed(), is that when doing
'/' farlook operations, curses_putmixed() and tty_putmixed() try to
display a character in the message window that looks exactly the same
as the one on the map, even if a symbol from a symset is being used
on the map, or when using ENHANCED_SYMBOLS.
Related note: curses_putmixed() matches the symbol and the color,
whereas tty_putmixed() (at present) does not attempt to match the
color.
299d49aebf