Autoconfigure use of terminfo

New configure --with-terminfo.  Before, terminfo was assumed to be
available everywhere but on Windows.

m4/my_termlib.m4

@@ -0,0 +1,25 @@
+AC_DEFUN([MY_CURSES_TERMINFO],
+[
+	AC_SEARCH_LIBS([setupterm], [termlib termcap curses ncurses],
+		[have_terminfo=yes], [have_terminfo=no])
+	AC_CHECK_HEADER([curses.h], , [have_terminfo=no])
+	AC_CHECK_HEADER([term.h], , [have_terminfo=no])
+	if test "$have_terminfo" = yes
+	then AC_DEFINE([HAVE_CURSES_TERMINFO], 1,
+		[Define if you have the curses interface to terminfo])
+	fi
+])
+
+AC_DEFUN([MY_WITH_TERMINFO],
+[
+	AC_ARG_WITH([terminfo],
+		AS_HELP_STRING([--with-terminfo],
+			[use terminfo for highlighting (default check)]))
+	if test "x$with_terminfo" != xno; then
+		MY_CURSES_TERMINFO
+		if test "$have_terminfo$with_terminfo" = noyes
+		then AC_MSG_FAILURE([Can't satisfy --with-terminfo])
+		fi
+		with_terminfo="$have_terminfo"
+	fi
+])