gcctoolchain: ensure that arch is passed just once

the first architecture is kept, and used.

Change-Id: I30d0f1f98b0ad53c2133aa9b7da14c86f21de25c
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
CPaster: Fix expiry parameter

Change-Id: I0e63e14e723b9b6bbf68350cf2c2d6ac1e223613
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>