mds: MDSAuthCaps: init "read" param in default constructor

CID 1244228:  Uninitialized scalar field  (UNINIT_CTOR)
/mds/MDSAuthCaps.h: 29 in MDSCapSpec::MDSCapSpec()()

Signed-off-by: Greg Farnum <greg@inktank.com>
mds: MDirUpdate: initialize discover count to 0 if we're not discovering

Otherwise it's left uninitialized and could do who-knows-what!

CID 1244229:  Uninitialized scalar field  (UNINIT_CTOR)
/messages/MDirUpdate.h: 55 in MDirUpdate::MDirUpdate(mds_rank_t, dirfrag_t,
int, std::set<int, std::less<int>, std::allocator<int>> &, filepath &, bool)()

Signed-off-by: Greg Farnum <greg@inktank.com>
Merge pull request #2677 from ceph/wip-mds-coverity

Wip mds coverity