Disallow w32 builds --without-toolkit-scroll-bars.

 configure.ac (HAVE_W32): Abort with error message if
 --without-toolkit-scroll-bars was specified.  See
 http://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00525.html
 for the details.

ChangeLog

+2015-01-20  Eli Zaretskii  <eliz@gnu.org>
+
+	* configure.ac (HAVE_W32): Abort with error message if
+	--without-toolkit-scroll-bars was specified.  See
+	http://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00525.html
+	for the details.
+
 2015-01-01  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* .gitattributes: New file.

configure.ac

@@ -1841,6 +1841,9 @@ CM_OBJ="cm.o"
 XARGS_LIMIT=
 if test "${HAVE_W32}" = "yes"; then
   AC_DEFINE(HAVE_NTGUI, 1, [Define to use native MS Windows GUI.])
+  if test "$with_toolkit_scroll_bars" = "no"; then
+    AC_MSG_ERROR([Non-toolkit scroll bars are not implemented for w32 build.])
+  fi
   AC_CHECK_TOOL(WINDRES, [windres],
                 [AC_MSG_ERROR([No resource compiler found.])])
   W32_OBJ="w32fns.o w32menu.o w32reg.o w32font.o w32term.o"