Fix cursesw detection

On systems which do not provide ncursesw.pc and whose /usr/include/curses.h
does not include wide support, we should not only try with no -I, i.e.
/usr/include, but also with -I/usr/include/ncursesw.

To properly detect for wide support with and without -Werror, we need to
check for the presence of e.g. the WACS_DEGREE macro.

We also want to stop at the first curses_inc_list configuration which works,
and make sure to set IFS to : at each new loop.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Tested-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Message-id: 20161109102752.13255-1-samuel.thibault@ens-lyon.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/configure b/configure
index fd6f898..7d2a34e 100755
--- a/configure
+++ b/configure
@@ -2926,7 +2926,7 @@
     curses_inc_list="$($pkg_config --cflags ncurses 2>/dev/null):"
     curses_lib_list="$($pkg_config --libs ncurses 2>/dev/null):-lpdcurses"
   else
-    curses_inc_list="$($pkg_config --cflags ncursesw 2>/dev/null):"
+    curses_inc_list="$($pkg_config --cflags ncursesw 2>/dev/null):-I/usr/include/ncursesw:"
     curses_lib_list="$($pkg_config --libs ncursesw 2>/dev/null):-lncursesw:-lcursesw"
   fi
   curses_found=no
@@ -2941,11 +2941,13 @@
   resize_term(0, 0);
   addwstr(L"wide chars\n");
   addnwstr(&wch, 1);
+  add_wch(WACS_DEGREE);
   return s != 0;
 }
 EOF
   IFS=:
   for curses_inc in $curses_inc_list; do
+    IFS=:
     for curses_lib in $curses_lib_list; do
       unset IFS
       if compile_prog "$curses_inc" "$curses_lib" ; then
@@ -2955,6 +2957,9 @@
         break
       fi
     done
+    if test "$curses_found" = yes ; then
+      break
+    fi
   done
   unset IFS
   if test "$curses_found" = "yes" ; then