cmake/cephfs: fix options to enable client and dependencies

cmake/cephfs: fix options to enable client and dependencies

invoking cmake with -DWITH_LIBCEPHFS=OFF fails to configure the client target:

CMake Error at src/client/CMakeLists.txt:13 (target_link_libraries):
  Target "client" links to:

    Boost::locale

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

because the client target is not conditional on WITH_LIBCEPHFS in src/CMakeLists.txt:

add_subdirectory(client)

if(WITH_LIBCEPHFS)

because client is also needed for ceph-fuse, make the client and its
dependencies depend on WITH_LIBCEPHFS OR WITH_FUSE

Signed-off-by: Casey Bodley <cbodley@redhat.com>
(cherry picked from commit 70eb1d64ac1ea6e7202d42571f83c34d3758ad8f)