dropping collada-dom dependent packages

recipes-ros/packagegroups/packagegroup-ros-world.bb

@@ -65,8 +65,6 @@ RDEPENDS_${PN} = "\
     hardware-interface \
     joint-limits-interface \
     transmission-interface \
-    collada-parser \
-    collada-urdf \
     kdl-parser \
     resource-retriever \
     urdf-parser-plugin \
@@ -175,6 +173,7 @@ RDEPENDS_${PN} = "\
     rosbridge-suite \
     "
 
+# collada-parser and collada-urdf require collada-dom, which does not compile with gcc6.
 # ar-track-alvar does not compile due to unknown opencv identifiers.
 # image-view requires gtk+, but it cannot be found by cmake for some reason.
 # sound-play requires python-gst (which is not available in any layers' master branch)