update corosync to 2.4.2

update corosync to 2.4.2

minor update with buildfixes for newer systems (strech, at least with
arm), config parser bugs and some qdevice fixes, while we do not have
qdevice enabled.

oneline log between v2.4.0 and v2.4.2:

96f91f2 libvotequorum: Bump version
19e48a6 [build] Fix build on RHEL7.3 latest
52e6ae5 cfg: Prevents use of uninitialized buffer
b0c850f Qnetd LMS: Fix two partition use case
0da1b74 man: mention qdevice incompatibilites in votequorum.5
49a9f72 Man: Fix corosync-qdevice-net-certutil link
87c363b Spec: Qdevice require same version of corosync
f837f95 Config: Flag config uidgid entries
3e995cf cts: Make it run with pacemaker-1.13+
71c9035 Low: totemsrp: Addition of the log.
a275d88 qdevice: some more small man page fixes
b6c71aa qdevice: Fix 'tie_breaker' in man page

Tested for a week now in cluster setups with mixed versions (v2.4.0
and v2.4.2) and upgrade tests.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>