Fix warnings

Author: nyalldawson

src/ui/qgssymbolv2selectordialogbase.ui

@@ -239,14 +239,10 @@
         </widget>
        </item>
       </layout>
-      <zorder></zorder>
       <zorder>frame</zorder>
       <zorder>line</zorder>
-      <zorder></zorder>
-      <zorder></zorder>
       <zorder>frame</zorder>
       <zorder>line</zorder>
-      <zorder></zorder>
      </widget>
     </widget>
    </item>

src/ui/symbollayer/widget_gradientfill.ui

@@ -536,7 +536,6 @@
   <zorder>mRefPoint1XDDBtn</zorder>
   <zorder>mRefPoint1YDDBtn</zorder>
   <zorder>mRefPoint2CentroidDDBtn</zorder>
-  <zorder>verticalSpacer</zorder>
  </widget>
  <customwidgets>
   <customwidget>

src/ui/symbollayer/widget_shapeburstfill.ui

@@ -389,21 +389,16 @@
   <zorder>label_6</zorder>
   <zorder>label_2</zorder>
   <zorder>radioTwoColor</zorder>
-  <zorder></zorder>
   <zorder>radioColorRamp</zorder>
   <zorder>label_3</zorder>
   <zorder>mRadioUseWholeShape</zorder>
   <zorder>mRadioUseMaxDistance</zorder>
   <zorder>mIgnoreRingsCheckBox</zorder>
   <zorder>mRadioUseWholeShape</zorder>
-  <zorder></zorder>
-  <zorder></zorder>
-  <zorder></zorder>
   <zorder>mStartColorDDBtn</zorder>
   <zorder>mEndColorDDBtn</zorder>
   <zorder>btnChangeColor</zorder>
   <zorder>btnChangeColor2</zorder>
-  <zorder>verticalSpacer</zorder>
   <zorder>mShadeWholeShapeDDBtn</zorder>
   <zorder>mShadeDistanceDDBtn</zorder>
   <zorder>mIgnoreRingsDDBtn</zorder>