libceph, ceph: implement msgr2.1 protocol (crc and secure modes)

Implement msgr2.1 wire protocol, available since nautilus 14.2.11
and octopus 15.2.5.  msgr2.0 wire protocol is not implemented -- it
has several security, integrity and robustness issues and therefore
considered deprecated.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/net/ceph/Makefile b/net/ceph/Makefile
index df02bd8..8802a0c 100644
--- a/net/ceph/Makefile
+++ b/net/ceph/Makefile
@@ -15,4 +15,4 @@
 	auth_x.o \
 	ceph_strings.o ceph_hash.o \
 	pagevec.o snapshot.o string_table.o \
-	messenger_v1.o
+	messenger_v1.o messenger_v2.o