fix build error and a warning

Author: jef-n

src/core/qgsexpression.cpp

@@ -950,6 +950,9 @@ static QVariant fcnRound( const QVariantList& values , QgsFeature *f, QgsExpress
 
 static QVariant fcnPi( const QVariantList& values , QgsFeature *f, QgsExpression* parent )
 {
+  Q_UNUSED( values );
+  Q_UNUSED( f );
+  Q_UNUSED( parent );
   return M_PI;
 }
 

src/ui/symbollayer/widget_ellipse.ui

@@ -65,7 +65,7 @@
       </widget>
      </item>
      <item row="0" column="1">
-      <widget class="QgsColorButtonV2" name="btnChangeColorBorder">
+      <widget class="QgsColorButton" name="btnChangeColorBorder">
        <property name="text">
         <string>Change</string>
        </property>
@@ -86,7 +86,7 @@
       </widget>
      </item>
      <item row="1" column="1">
-      <widget class="QgsColorButtonV2" name="btnChangeColorFill">
+      <widget class="QgsColorButton" name="btnChangeColorFill">
        <property name="text">
         <string>Change</string>
        </property>

src/ui/symbollayer/widget_linepatternfill.ui

@@ -125,7 +125,7 @@
     </widget>
    </item>
    <item row="7" column="1">
-    <widget class="QgsColorButtonV2" name="mColorPushButton">
+    <widget class="QgsColorButton" name="mColorPushButton">
      <property name="text">
       <string>Change</string>
      </property>

src/ui/symbollayer/widget_simplefill.ui

@@ -143,14 +143,14 @@
       </widget>
      </item>
      <item row="2" column="1">
-      <widget class="QgsColorButtonV2" name="btnChangeBorderColor">
+      <widget class="QgsColorButton" name="btnChangeBorderColor">
        <property name="text">
         <string>Change</string>
        </property>
       </widget>
      </item>
      <item row="0" column="1">
-      <widget class="QgsColorButtonV2" name="btnChangeColor">
+      <widget class="QgsColorButton" name="btnChangeColor">
        <property name="text">
         <string>Change</string>
        </property>