Merge pull request #3666 from xroche/master

Added ceph_flock() to libcephfs.

diff --cc src/client/Client.cc
Simple merge

diff --cc src/client/Client.h
Simple merge

diff --cc src/include/cephfs/libcephfs.h
Simple merge

diff --cc src/test/CMakeLists.txt
Simple merge

diff --cc src/test/Makefile.am
Simple merge