BUILD: threads: add the definition of PROTO_LOCK

This one was added by commit daacf3664 ("BUG/MEDIUM: protocols: add a
global lock for the init/deinit stuff") but I forgot to add it to the
include file, breaking DEBUG_THREAD.

(cherry picked from commit d6e0c03384cab2c72fb6ab841420045108ea4e6f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/include/common/hathreads.h b/include/common/hathreads.h
index a7c8dc9..b05215b 100644
--- a/include/common/hathreads.h
+++ b/include/common/hathreads.h
@@ -562,6 +562,7 @@
 	AUTH_LOCK,
 	LOGSRV_LOCK,
 	DICT_LOCK,
+	PROTO_LOCK,
 	OTHER_LOCK,
 	LOCK_LABELS
 };
@@ -679,6 +680,7 @@
 	case AUTH_LOCK:            return "AUTH";
 	case LOGSRV_LOCK:          return "LOGSRV";
 	case DICT_LOCK:            return "DICT";
+	case PROTO_LOCK:           return "PROTO";
 	case OTHER_LOCK:           return "OTHER";
 	case LOCK_LABELS:          break; /* keep compiler happy */
 	};