ProjectExplorer: Add a "C" file icon overlay

Change-Id: Id73a482fb50f8b937f2a16395fe1b43a656c49f4
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/projectexplorer/projectexplorer.qrc

@@ -70,6 +70,8 @@
         <file>images/fileoverlay_ui@2x.png</file>
         <file>images/fileoverlay_scxml.png</file>
         <file>images/fileoverlay_scxml@2x.png</file>
+        <file>images/fileoverlay_c.png</file>
+        <file>images/fileoverlay_c@2x.png</file>
         <file>images/fileoverlay_cpp.png</file>
         <file>images/fileoverlay_cpp@2x.png</file>
         <file>images/fileoverlay_h.png</file>

src/plugins/projectexplorer/projectexplorerconstants.h

@@ -223,6 +223,7 @@ const char FILEOVERLAY_MODULES[] = ":/projectexplorer/images/fileoverlay_modules
 const char FILEOVERLAY_QML[]=":/projectexplorer/images/fileoverlay_qml.png";
 const char FILEOVERLAY_UI[]=":/projectexplorer/images/fileoverlay_ui.png";
 const char FILEOVERLAY_QRC[]=":/projectexplorer/images/fileoverlay_qrc.png";
+const char FILEOVERLAY_C[]=":/projectexplorer/images/fileoverlay_c.png";
 const char FILEOVERLAY_CPP[]=":/projectexplorer/images/fileoverlay_cpp.png";
 const char FILEOVERLAY_H[]=":/projectexplorer/images/fileoverlay_h.png";
 const char FILEOVERLAY_SCXML[]=":/projectexplorer/images/fileoverlay_scxml.png";

src/tools/icons/qtcreatoricons.svg

@@ -8897,7 +8897,7 @@
       <path
          style="fill:none;fill-rule:evenodd;stroke:#2e5e84;stroke-width:1px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
          d="m 106,528.5 c -2.5,0 -3.5,0.5 -3.5,2.5 0,2 1,2.5 3.5,2.5"
-         id="path5929"
+         id="fileoverlay_c"
          inkscape:connector-curvature="0"
          sodipodi:nodetypes="czc" />
       <path
@@ -9089,6 +9089,32 @@
            sodipodi:nodetypes="ccccc" />
       </g>
     </g>
+    <g
+       transform="translate(160)"
+       id="src/plugins/projectexplorer/images/fileoverlay_c">
+      <use
+         x="0"
+         y="0"
+         xlink:href="#use2538"
+         id="use4568"
+         width="100%"
+         height="100%"
+         transform="translate(32)" />
+      <path
+         style="opacity:0.75;fill:#ffffff;stroke:none"
+         d="m 108,527 c -2,0 -4,1 -4,4 0,3 2,4 4,4 2,0 2,-0.5 2,-1.5 0,-1 -0.5,-1.5 -2,-1.5 -1.5,0 -1.5,-2 0,-2 1.47084,0 2,-0.5 2,-1.5 0,-1 0,-1.5 -2,-1.5 z"
+         id="path4240"
+         inkscape:connector-curvature="0"
+         sodipodi:nodetypes="zzzssssz" />
+      <use
+         x="0"
+         y="0"
+         xlink:href="#fileoverlay_c"
+         id="use6079"
+         width="100%"
+         height="100%"
+         transform="translate(3)" />
+    </g>
     <g
        id="src/libs/utils/images/filesave">
       <rect