gnrc_netif: expose message queue size configurable

[miri64]

Contribution description

In some offline discussions regarding #10268 we noticed, that the message queue size is too small for some network devices to handle large fragmented packages. Not just the driver in #10268 is affected, but also e.g. the kw2x on pba-d-01-kw2x. This change

1. Increases the queue size from 8 to 16 for gnrc_netif threads and
2. Exposes the macro for the message queue size and makes it configurable. (see gnrc_netif: expose message queue size configurable #11067 (comment)).

Testing procedure

Compile and flash examples/gnrc_networking to pba-d-01-kw2x with CFLAGS=-DGNRC_NETIF_MSG_QUEUE_SIZE=16, try to ping it from another IEEE-802.15.4-capable board with large payloads:

ping6 -s 1232 "<link-local address>"

Without this PR problems might arise, with it, it should work. Also try and see if for smaller boards (e.g. z1 or arduino-mega2560) examples/gnrc_minimal still works without stack overflows (you can't send too huge packets though, as the packet buffer size is set to 512 in gnrc_minimal) (gnrc_minimal does not work in master, see #11067 (comment)).

Issues/PRs references

Discovered in #10268.

[kaspar030]

Previous setting was 8. Would make sense to keep that value.

[kaspar030]

ah, nvm, PR text describes the change. ok as is.

[miri64]

See OP:

1. Increases the queue size from 8 to 16 for gnrc_netif threads and

Also I put the change of the message queue size in a separate commit + added testing procedure description to account for the change ;-).

[kaspar030]

ACK.

[miri64]

gnrc_minimal doesn't work on z1 :-/.

[miri64]

At least (on master) it doesn't reply to ping requests :-/.

[miri64]

gnrc_minimal is also not pingable on samr21-xpro... :(

[miri64]

Better safe than sorry. I reverted the message queue size change...

[miri64]

@kaspar030 can you have another look. The change now should be very simple.

[SemjonWilke]

Successfully tested with ping from samr21-xpro -> pba-d-01-kw2x and samr21-xpro -> nrf52840dk (#10268) both with 1232 Bytes.
ping6 "<link-local address>" -s 1232

[kaspar030]

(re-)ACK.

[kaspar030]

waidaminute. shouldn't the original define be removed somewhere?

[miri64]

Sorry... must have happened when I removed the size change >_<

[miri64]

Fixed and amended immediately.

[kaspar030]

&go.

[miri64]

gnrc_minimal is also not pingable on samr21-xpro... :(

For reference: this is because gnrc_minimal is not including gnrc_sixlowpan_iphc is not including IPHC, so the pinging node needs to deactivate iphc. This is also documented in the example's README