bp: don't insist on unique name for ns_memcached_sup instances

Which breaks multiple buckets because every bucket creates its own
instance of ns_memcached_sup which all try to register under same name
and fail.

Change-Id: I4cff4d6db4706ae4b529b832916dc7cff5d3918d
Orig-Reviewed-on: http://review.couchbase.org/42433
Reviewed-on: http://review.couchbase.org/42995
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
bp: MB-9890: cleanup keys/bodies from xdcr_vbucket_rep crash reports

I.e. so that we cannot leak customer data there

Change-Id: I23647d34f8bb8b44fc51bedbd9cae4e9aa41e04c
Orig-Reviewed-on: http://review.couchbase.org/42490
Reviewed-on: http://review.couchbase.org/42996
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
bp: remove unnecessary opening/closing of master db from xdc_vbucket_rep

Change-Id: Ia350ba648740b4aacca52dabf2235d202ecf96a1
Orig-Reviewed-on: http://review.couchbase.org/41934
Reviewed-on: http://review.couchbase.org/42997
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
bp: MB-9890: avoid logging states of xdc_vbucket_rep childs

When xdc_vbucket_rep process exits it triggers proc_lib code that
dumps exit reason and other convenience diagnostic. Part of that
diagnostics is dump of neighbor process states that don't trap
exits. And worker sub-processes of xdc_vbucket_rep are such processes
that don't trap exits.

So in order to prevent proc_lib from exposing internals of those
workers, we create them via intermediate processes that do trap exits.

Change-Id: I68e13786568a5fba336b59500b2189807f047ce0
Orig-Reviewed-on: http://review.couchbase.org/42491
Reviewed-on: http://review.couchbase.org/42998
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>