- Fix compilation on OpenBSD about `#ifdef` (@omegametabroccolo, @hannesm,

@reynir, #614, related with #600)

- Add GitHub actions to test Solo5 on different platforms (@hannesm, #616, #617

& #540)

- Do not use `-Wstringopt-overflow` when we use `clang` for `test_ssp`

(@hannesm, #607)

- Show errors and exit instead of `assert false` (@shym, @edwintorok, @hannesm,

@reynir, #613 & #612)

- Define `.note.GNU-stack` when it's needed (@shym, @Kensan, @hannesm, @palainp,

@dinosaure, #619, #570 & #562)

- Detect MTU on TAP interface for hvt, spt and virtio (@reynir, @hannesm,

@dinosaure, #605 & #606)

- Adapt OpenBSD hvt tender with the new `vmm(4)` (@omegametabroccolo, @hannesm,

#600)