exec: Merge install_exec_creds into setup_new_exec

The two functions are now always called one right after the
other so merge them together to make future maintenance easier.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/events/core.c

@@ -12217,7 +12217,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
  * When a child task exits, feed back event values to parent events.
  *
  * Can be called with exec_update_mutex held when called from
- * install_exec_creds().
+ * setup_new_exec().
  */
 void perf_event_exit_task(struct task_struct *child)
 {