GUI: Fix the gui.cppcheck to work with GUI.

The project file to check just GUI code was missing the directory
to check. This is probably due it was used originally as
"automatically" loaded project file which assumed current
directory is checked and only added some additional parameters.

gui/gui.cppcheck

@@ -4,4 +4,10 @@
         <dir name="../lib"/>
         <dir name="temp"/>
     </includedir>
+    <paths>
+        <dir name="."/>
+    </paths>
+    <ignore>
+        <path name="temp/"/>
+    </ignore>
 </project>