creds: protobuf -- Move @creds_entry into @thread_core_entry

Creds are per-thread data, declare them appropriately.
We will need this data to restore threads with different
credentials.

(In a scope of https://jira.sw.ru/browse/PSBM-41416)
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

protobuf/core.proto

@@ -5,6 +5,7 @@ import "core-ppc64.proto";
 
 import "rlimit.proto";
 import "timer.proto";
+import "creds.proto";
 
 import "siginfo.proto";
 
@@ -75,6 +76,7 @@ message thread_core_entry {
 	optional uint32			pdeath_sig	= 8;
 
 	optional signal_queue_entry	signals_p	= 9;
+	optional creds_entry		creds		= 10;
 }
 
 message task_rlimits_entry {