Qt: fix .ui names conflicts and warnings

modules/gui/qt4/ui/open.ui

@@ -220,7 +220,7 @@
        <widget class="Line" name="line"/>
       </item>
       <item row="3" column="1" colspan="5">
-       <widget class="Line" name="line"/>
+       <widget class="Line" name="line_1"/>
       </item>
       <item row="0" column="4" colspan="2">
        <widget class="QTimeEdit" name="startTimeTimeEdit">

modules/gui/qt4/ui/sprefs_audio.ui

@@ -450,7 +450,7 @@
            <property name="enabled">
             <bool>true</bool>
            </property>
-           <layout class="QGridLayout" name="gridLayout">
+           <layout class="QGridLayout" name="gridLayout_1">
             <property name="margin">
              <number>0</number>
             </property>

modules/gui/qt4/ui/sprefs_video.ui

@@ -166,7 +166,7 @@
         <property name="title">
          <string>Video</string>
         </property>
-        <layout class="QGridLayout" name="gridLayout">
+        <layout class="QGridLayout" name="gridLayout_1">
          <item row="0" column="0">
           <widget class="QLabel" name="deinterLabel">
            <property name="text">

modules/gui/qt4/ui/video_effects.ui

@@ -956,7 +956,7 @@
       <property name="checked">
        <bool>false</bool>
       </property>
-      <layout class="QGridLayout" name="gridLayout">
+      <layout class="QGridLayout" name="gridLayout_1">
        <item row="0" column="0">
         <widget class="QLabel" name="label_19">
          <property name="minimumSize">