ios: fix iosrunconfiguration m_arguments persistency

Change-Id: I11b719725ed788cbdd97b0e64d69880949634905
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>