MB-12762: Close SSL connection on error during handshake

If a receive error occured during SSL handshake (e.g. received
incorrect handshake data) then instead of closing the connection (as
expected) memcached would belive it needed to retry and return the
connection to the conn_read state. This resulted in the state machine
for the connection essentially looping forever attempting to read
data. This has two observabl side-effects:

1) A connection slot is essentially consumed (forever) by the failed
   connection attempt.

2) The frontend thread that the failed connection was assigned to will
   spin (at 100% CPU), if no other connections owned by the worker have
   any events waiting.

(Note for (2), the CPU isn't "consumed" - other connections if present
*will* be serviced as normal, the issue is simply that the failed
connection immediately posts an event to retry the read, which
libevent will immediately schedule if there are no other events
(i.e. other connections) ready).

Fix is to ensure that the ssl.error status is checked after draining
the SSL recv pipe, and if set then reseting the connection.

Change-Id: Ieb7e689a207e592a68fc5ee998a43d714c4050b0
Reviewed-on: http://review.couchbase.org/43604
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Don't report error on cleanly closed SSL connections

When reading from an SSL connection, check for normal (clean)
connection close; don't report it as an error.

Change-Id: Ia4912489cafc893fa237b165be011fe13c28f711
Reviewed-on: http://review.couchbase.org/43605
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Use @ instad of _ in predefined roles

Change-Id: I2e30b0b457b05d6674ed7e1182f855ee7c0d2532
Reviewed-on: http://review.couchbase.org/43663
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Add base breakpad code. Dumps on crash.
  - Tidy up, sort out stack vs heap issue, platform support++
    - Merge @at's Windows code
  - Uses proper memcached logging as callback for exception_handler

Change-Id: I00de005b96dbd8517192aa26b1cbd5b9e464e9bf