do not use white text on white background in control

... setting a control's background color has no effect (until input
field text is changed?)

Could be observed in the pivot table dialog's source range edit when an
invalid range was entered.

Change-Id: Iafb2a9016ac6bd4c020273911d62dd7423ee0458
(cherry picked from commit 01a93d34)
Reviewed-on: https://gerrit.libreoffice.org/19354Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

formula/source/ui/dlg/funcutl.cxx

@@ -519,8 +519,14 @@ void RefEdit::SetRefValid(bool bValid)
     }
     else
     {
+#if 0
+        // Setting background color has no effect here so we'd end up with
+        // white on white!
         SetControlForeground(COL_WHITE);
         SetControlBackground(0xff6563);
+#else
+        SetControlForeground( ::Color( RGB_COLORDATA( 0xf0, 0, 0)));
+#endif
     }
 }