Rewritten the readline test, hopefully it's okay now.

configure.in

@@ -243,38 +243,67 @@ AC_MSG_RESULT($withval)
 LIBS="$withval $LIBS"
 ], AC_MSG_RESULT(no))
 
-AC_MSG_CHECKING(for --with-readline)
-AC_ARG_WITH(readline, [--with-readline[=DIRECTORY] use GNU readline library], [
-AC_MSG_RESULT($withval)
-AC_DEFINE(WITH_READLINE)
-if test -d "$withval"
-then LDFLAGS="$LDFLAGS -L$withval"
+AC_MSG_CHECKING(for --with(out)-readline)
+use_readline="yes"
+AC_ARG_WITH(readline,
+[--with-readline=DIRECTORY search GNU readline library in DIRECTORY
+--without-readline        do not use GNU readline library],
+[AC_MSG_RESULT($withval); use_readline="$withval"],
+[AC_MSG_RESULT((default) yes)])
+if test "$use_readline" != "no"
+then
+	if test "$use_readline" != "yes"
+	then add_ldflags="-L$use_readline"
+	else add_ldflags=""
 	fi
-# first check if we can compile without lib termcap
-AC_MSG_CHECKING(for -lreadline without -ltermcap)
-# check if a libreadline exists
-LIBS="$LIBS -lreadline"
-AC_TRY_LINK(extern char *readline();,char *line=readline();,[
-      AC_MSG_RESULT(yes)],[
-      AC_MSG_RESULT(no)
-      AC_CHECKING(for -lreadline that needs -ltermcap)
-      termcap=
-      AC_CHECK_LIB(termcap, tgetent, [termcap=termcap], [
-      AC_CHECK_LIB(termlib, tgetent, [termcap=termlib], [
-      AC_ERROR(no working -ltermcap/termlib found -- do not use --with-readline)])])
-      # Avoid possible conflict between shared libraries termcap and gl
-      # on IRIX 5: both contain a routine called clear.
-      if test -f /usr/lib/lib$termcap.a
-      then LIBS="$LIBS /usr/lib/lib$termcap.a"
-      else LIBS="$LIBS -l$termcap"
+	# See where the termcap interface could be hiding...
+	AC_MSG_CHECKING(for readline and termcap libraries)
+	AC_CACHE_VAL(ac_cv_readline_termcap,
+		[
+		AC_MSG_RESULT(have to find out)
+		save_libs="$LIBS"
+		save_ldflags="$LDFLAGS"
+		LDFLAGS="$save_ldflags $add_ldflags"
+		rl="-lreadline"
+		first=""
+		# Hack for SGI IRIX 5.x.
+		# Both termcap and gl have an entry point clear().
+		# When linking with both shared libraries, we're in trouble.
+		# We don't need the one in termcap.
+		# By forcing a static link for termcap, we avoid
+		# linking its clear() entry point.
+		if test -f /usr/lib/libgl.so -a -f /usr/lib/libtermcap.a
+		then first="/usr/lib/libtermcap.a"
 		fi
-      AC_MSG_CHECKING(for -lreadline)
-      AC_TRY_LINK(extern char *readline();, char *line=readline();,[
-         AC_MSG_RESULT(yes)],[
-	 AC_ERROR(no working GNU readline library found -- do not use --with-readline)])
+		for add_lib in \
+			"$first" "-ltermcap" "-ltermlib" "-lcurses" "-lncurses"
+		do
+			AC_MSG_CHECKING(for $rl $add_lib)
+			LIBS="$save_libs $rl $add_lib"
+			AC_TRY_LINK([extern char *readline();],
+			    [char *line=readline();],
+			    [AC_MSG_RESULT(yes);
+			     ac_cv_readline_termcap="$rl $add_lib"],
+			    [AC_MSG_RESULT(no)])
+			if test "$ac_cv_readline_termcap" != ""
+			then break
+			fi
+		done
+		LIBS="$save_libs"
+		LDFLAGS="$save_ldflags"
+		AC_MSG_CHECKING(result from check for readline and termcap)
 		])
-],
-AC_MSG_RESULT(no))
+	if test "$ac_cv_readline_termcap" = ""
+	then
+		AC_MSG_RESULT(no)
+		AC_MSG_WARN(cannot link with GNU readline -- see config.log)
+	else
+		AC_MSG_RESULT($ac_cv_readline_termcap)
+		LIBS="$LIBS $ac_cv_readline_termcap"
+		LDFLAGS="$LDFLAGS $add_ldflags"
+		AC_DEFINE(WITH_READLINE)
+	fi
+fi
 
 AC_MSG_CHECKING(for --with-thread)
 AC_ARG_WITH(thread, [--with-thread[=DIRECTORY] make interpreter thread-safe], [