Update CMakeLists.txt
Update CMakeLists.txt

Former-commit-id: 63168f689d35df20c842f45026d92f8887d9eff7
clab/dynet,shuheik/dynet,clab/cnn,shuheik/dynet,xunzhang/dynet,xunzhang/dynet,clab/dynet,xunzhang/dynet,danielhers/dynet,chunyang-wen/dynet,danielhers/dynet,clab/dynet,clab/cnn,shuheik/dynet,danielhers/dynet,chunyang-wen/dynet,shuheik/dynet,shuheik/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,xunzhang/dynet,shuheik/dynet,danielhers/dynet,danielhers/dynet,clab/cnn,chunyang-wen/dynet,clab/dynet,clab/dynet,chunyang-wen/dynet,shuheik/dynet,clab/dynet