Message "collection" support

[Dan Williams]

On Wed, 2020-04-15 at 21:56 +0200, Aleksander Morgado wrote:
> Hey!
> 
> I've prepared a branch that allows building "tailored" libqmi
> libraries, i.e. selecting just a subset of all the available
> commands.
> See:
> 
> https://gitlab.freedesktop.org/mobile-broadband/libqmi/-/merge_requests/109
> 
> By default it would have 3 different collections: "minimal", with
> just
> a few messages required for basic functionality (e.g. if you're going
> to use qmi-network), "basic" if you need further functionalities like
> qmi-firmware-update or integration with ModemManager, and "full" with
> all current supported messages.
> 
> Users building their own systems can patch libqmi by adding a new
> custom collection file under e.g. /data/qmi-collection-vendor.json,
> and will then be able to configure using --enable-collection=vendor.
> 
> When a collection is selected, only the messages in the collection
> are
> included in the library *and* in qmicli, this is, qmicli also gets
> tailored for the custom message subset.
> 
> These are the minimal and basic collections included:
> https://gitlab.freedesktop.org/aleksm/libqmi/-/blob/aleksander/collections/data/qmi-collection-minimal.json
> https://gitlab.freedesktop.org/aleksm/libqmi/-/blob/aleksander/collections/data/qmi-collection-basic.json
> 
> The code in qmicli gets a bit polluted with #ifdefs but I believe
> that
> the benefit is bigger than the maintenance burden it carries.
> 
> The main reasoning for this is that there are systems with limited
> available memory or disk space, and libqmi is not really optimized in
> that regard right now. In the build tests I've done in different
> systems, I've seen a reduction of file size of up to 50% when using
> the basic collection w.r.t. the full collection.
> 
> Standard distributions should definitely pick the "full" collection,
> though.
> 
> What do you all think?

Works for me, if size is really a blocker in some systems.

Dan