EXP-1430 FIX -- Minimizing voice settings floater corrupts layout throughout rest of session

* Added minimum size for layout panel that holds voice morphing and removed
  user resizability.

Reviewed by Richard.

indra/newview/skins/default/xui/en/floater_voice_controls.xml

@@ -89,7 +89,7 @@
              visible="true"
              width="20" />
         </layout_panel>
-        <layout_panel name="leave_call_panel" height="26" auto_resize="false">
+        <layout_panel name="leave_call_panel" height="26" min_height="26" user_resize="false" auto_resize="false">
         <layout_stack
          clip="true"
          follows="left|top|right"