ssl_factory: avoid a non-POD (vector<>) in static storage
ssl_factory: avoid a non-POD (vector<>) in static storage

The global vector<Mutex*> in static storage was causing ASAN test
failures when I looped rpc-test's keepalive test with SSL enabled[1].
The issue is that the static storage destructor could run concurrently
with other threads still trying to access the SSL mutexes.

Since this mutex list is purposefully leaked anyway, it's better to just
use a C-style array.

[1] http://dist-test.cloudera.org/job?job_id=todd.1480910327.10622

Change-Id: I859aefd932d62fa8619650fcc795d3676187ceb4
Reviewed-on: http://gerrit.cloudera.org:8080/5354
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Tested-by: Kudu Jenkins

EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu,andrwng/kudu,EvilMcJerkface/kudu,cloudera/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,cloudera/kudu,EvilMcJerkface/kudu,helifu/kudu,InspurUSA/kudu,cloudera/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,InspurUSA/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,helifu/kudu,helifu/kudu,andrwng/kudu,EvilMcJerkface/kudu,helifu/kudu,EvilMcJerkface/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu