common: Debug ctdb_addr_to_str() using new function ctdb_external_trace()
We've seen this function report "Unknown family, 0" and then CTDB
disappeared without a trace. If we can reproduce it then this might
help us to debug it.
The idea is that you do something like the following in /etc/sysconfig/ctdb:
export CTDB_EXTERNAL_TRACE="/etc/ctdb/config/gcore_trace.sh"
When we hit this error than we call out to gcore to get a core file so
we can do forensics. This might block CTDB for a few seconds.
Signed-off-by: Martin Schwenke <martin@meltin.net>
(This used to be ctdb commit
7895bc003f087ab2f3181df3c464386f59bfcc39)