17810: drivers/slipdev: implement sleep states r=benpicco a=benpicco
18348: sys/net/gnrc/pktbuf_static: make use of alignas() r=maribu a=maribu
### Contribution description
Since we are now using C11, we can make use of `alignas()` provided by `<stdalign.h>` to make the alignment code easier to read.
### Testing procedure
I didn't expect this to change binaries, but is safes 4 bytes. `elf_diff` shows that the compiler (at least GCC 11.3.0) was not able to detect that `gnrc_pktbuf_static_buf` was just an alias for `_pktbuf_buf`. That makes sense since it would be hard without LTO to rule out external writes to `gnrc_pktbuf_static_buf`, unless one would have added a `const` (to the pointer, not to the data the pointer points to).
The [output of `elf_diff`](https://mari-bu.de/pr_18348_gnrc_pktbuf_static_elf_diff.html) looks otherwise quite unscary.
Also:
```
$ make BOARD=nucleo-f767zi -C tests/unittests/ tests-pktbuf flash test
make: Entering directory '/home/maribu/Repos/software/RIOT/tests/unittests'
Building application "tests_unittests" for "nucleo-f767zi" with MCU "stm32".
[...]
Welcome to pyterm!
Type '/exit' to exit.
READY
s
START
.............................................
OK (45 tests)
make: Leaving directory '/home/maribu/Repos/software/RIOT/tests/unittests'
```
### Issues/PRs references
None
19120: CI: seperate check-labels and check-commits workflows r=maribu a=kaspar030
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Co-authored-by: Kaspar Schleiser <kaspar@schleiser.de>
The macros CONCAT(), MIN(), and MAX() are defined over and over again in
RIOT's code base. This de-duplicates the code by moving the macros to a
common place.
18773: nanocoap_sock: fix handling empty ACKs with separate response r=maribu a=benpicco
Co-authored-by: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Co-authored-by: Benjamin Valentin <benjamin.valentin@bht-berlin.de>
If a NON confirmable message is sent with a callback function,
not receiving a response in time would lead to a retransmission.
This is of course an error, as only CON messages are to be retransmitted.
In situations with high packet loss, if all sync packets are lost, conflicting
subnets will be configured.
If the network is static, this can be prevented by always using the highest number
of subnets that has been observed.
This assumes no nodes are physically added / removed from the network.
