Add ability to store multiarch tuples
Instead of just having a single primary multiarch, now we are able to list multiple multiarch tuples. The first one will be considered the primary and all the others will be assumed to be "foreign" architectures.
This feature was added as part of T17194 !84 (merged) , but after a change of approach it was not needed anymore.
I'm putting this as a separate MR so that it will be easier to evaluate and discuss if we are still interested in having this feature or not.
/cc @smcv @jpwhiting
Edited by Ludovico de Nittis