add missing header

git-svn-id: https://svn.salilab.org/imp/trunk@16155 e91f8c7b-0e32-4433-a9ac-4502d39a4eab
add missing include

git-svn-id: https://svn.salilab.org/imp/trunk@16156 e91f8c7b-0e32-4433-a9ac-4502d39a4eab