core: add nm_utils_get_start_time_for_pid() function

Move the code from nm-auth-subject.c over to NetworkManagerUtils.c

Signed-off-by: Thomas Haller <thaller@redhat.com>

src/NetworkManagerUtils.h

@@ -63,6 +63,8 @@ str_if_set (const char *str, const char *fallback)
 	return str ? str : fallback;
 }
 
+guint64 nm_utils_get_start_time_for_pid (pid_t pid);
+
 typedef void (*NMUtilsKillChildAsyncCb) (pid_t pid, gboolean success, int child_status, void *user_data);
 void nm_utils_kill_child_async (pid_t pid, int sig, guint64 log_domain, const char *log_name,
                                 guint32 wait_before_kill_msec,