Disable threading for formula groups for now.

Change-Id: Ic72762c030878158d505306cbdd9c50553feecfd
Reviewed-on: https://gerrit.libreoffice.org/49032Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

officecfg/registry/schema/org/openoffice/Office/Calc.xcs

@@ -1455,7 +1455,7 @@
           <info>
             <desc>Whether to use threaded calculation of formula groups when applicable.</desc>
           </info>
-          <value>true</value>
+          <value>false</value>
 	</prop>
 	<!-- Note: The default values below probably must correspond
 	to those assigned in setOpenCLConfigToDefault() in