setup.sh.in: honor $TMPDIR if it exists (fix #710)
setup.sh.in: honor $TMPDIR if it exists (fix #710)

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