cmake: conditionally install man pages

this matches its counterpart in automake
* install fuse related man pages only if HAVE_LIBFUSE
* install rbd related man pages only if WITH_RBD

Signed-off-by: Kefu Chai <kchai@redhat.com>

man/CMakeLists.txt

@@ -2,7 +2,6 @@ install(FILES
 	ceph-osd.8
 	ceph-mds.8
 	ceph-mon.8
-	ceph-fuse.8
 	ceph-syn.8
 	crushtool.8
 	osdmaptool.8
@@ -17,17 +16,28 @@ install(FILES
 	ceph-authtool.8
 	rados.8
 	librados-config.8
-	rbd.8
 	ceph-clsinfo.8
 	ceph-debugpack.8
 	cephfs.8
 	ceph-dencoder.8
 	ceph-rest-api.8
-	ceph-rbdnamer.8
 	ceph-post-file.8
+  DESTINATION ${CEPH_MAN_DIR}/man8)
+
+if(HAVE_LIBFUSE)
+  install(FILES
+	ceph-fuse.8
 	rbd-fuse.8
+	DESTINATION ${CEPH_MAN_DIR}/man8)
+endif()
+
+if(WITH_RBD)
+  install(FILES
+	ceph-rbdnamer.8
 	rbd-nbd.8
-	rbd-replay.8
 	rbd-replay-prep.8
+	rbd-replay.8
 	rbdmap.8
-  DESTINATION ${CEPH_MAN_DIR}/man8)
+	rbd.8
+	DESTINATION ${CEPH_MAN_DIR}/man8)
+endif()