It makes no sense to error out if the builder runs "./configure
--with-curses" and no option argument. "--with-curses" without an option
argument now keeps using the default name list for detecting ncurses
library.

Signed-off-by: Kang-Che Sung <[email protected]>

When "configure" suggests user to install pkg-config, output the
'*curses*.pc' file detected in the config.log. This aids diagnosing
the configure script.

Signed-off-by: Kang-Che Sung <[email protected]>

It is slightly more robust to grep for the 'pkg_m4_included' token when
running "make dist". Also, shorten the "make dist" warning message, and
tell users if they need to regenerate configure when we recommend them
to install pkg-config.

Signed-off-by: Kang-Che Sung <[email protected]>

When ncurses is compiled with reentrant support, the "stdscr" may be
only available as a macro and not a symbol for direct linking. We can
check for "stdscr" only after the curses headers are included. For now
we can remove the "stdscr" test when checking for keypad() function.

Signed-off-by: Kang-Che Sung <[email protected]>

According to ncurses man page, mvadd_wchnstr() may be implemented as a
macro.

Signed-off-by: Kang-Che Sung <[email protected]>

This allows configure tests to utilize the macro.
Also explain the reasons that we define _XOPEN_SOURCE_EXTENDED and not
_XOPEN_SOURCE.

Signed-off-by: Kang-Che Sung <[email protected]>

The main thing I intended to test is "stdscr", but it is also useful to
test ncurses functions that might be implemented as macros, such as
refresh() and mvadd_wchnstr().

Signed-off-by: Kang-Che Sung <[email protected]>

curses.h may define its own "bool" type, because the X/Open Curses
standard defines "bool" that predates C99 "bool". If curses.h "bool" is
not compatible with ISO C, fail at configure time.

(The C23 standard now makes "bool" a keyword so that a
"typedef /*whatever*/ bool;" is no longer portable. This is a bug that
curses implementations should fix.)

Solaris 11 is known to ship with a broken curses.h header (the default
curses, not ncurses).

Signed-off-by: Kang-Che Sung <[email protected]>

Now it can guess the terminfo library name based on the ncurses
library file name. E.g. "-ltinfow" for the corresponding"-lncursesw".
If the guessed library name doesn't link, try the "-ltinfo" name then.

Signed-off-by: Kang-Che Sung <[email protected]>

"ncursest" and "ncursestw" are multi-threaded variants of the ncurses
library. The "t" library names are only used in operating systems that
do not support weak symbols (so you won't see such names in Linux), but
the names are documented in ncurses anyway. Adding them to the list of
names to check won't hurt.

* See the curs_threads(3X) man page, and the INSTALL file from ncurses
  package. Notably the "--enable-reentrant", "--with-pthread" and
  "--enable-weak-symbols" options in ncurses.

Signed-off-by: Kang-Che Sung <[email protected]>