external_mini_cluster: log executable and flags
external_mini_cluster: log executable and flags

This is handy when diagnosing a linked_list-test failure, in particular.
The user can copy the flags from the log into a new terminal to restart
a tablet server or master on the same directory. It also makes it easier
to see in the logs where servers have been restarted.

Change-Id: If408ee664018479f4f1474a84f3cfff27f75530c
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2789
Reviewed-by: Michael Percy <e07a1fd797b473a9c849e618aa2ce06d8055760b@cloudera.com>
Tested-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@cloudera.com>

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