pie: A quick workaround for PR_SET_DUMPABLE == 2 restore error.

[ xemul: It's a temporary workaround not to lock the -rc2 release.
  Once we have some better solution, this will be rolled back. ]

Signed-off-by: Saied Kazemi <saied@google.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>