fix handling of cmake packages which do not install any files (fix #665)
fix handling of cmake packages which do not install any files (fix #665)

jack-oquin/catkin,ros/catkin,asmodehn/catkin,thaddeustaylor/catkin,scpeters/catkin,thaddeustaylor/catkin,shyamalschandra/catkin,beni55/catkin,beni55/catkin,jack-oquin/catkin,harmishhk/catkin,shyamalschandra/catkin,scpeters/catkin,wkentaro/catkin,wkentaro/catkin,scpeters/catkin,beni55/catkin,jack-oquin/catkin,shyamalschandra/catkin,ros/catkin,asmodehn/catkin,harmishhk/catkin,wkentaro/catkin,asmodehn/catkin,ros/catkin,harmishhk/catkin,thaddeustaylor/catkin