build_wrapper: Fix configure options for iOS

We need to be able to discriminate between iPhone and iPhoneSimulator
by using the RELEASE_BUILD_QT_CONFIGURE_OPTIONS_FILE env var.

Also fixing the use of EXTRA_QT_CONFIGURE_OPTIONS

Change-Id: Ieb232420fbfa22fd16cff46670127a77a955d584
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>