[gitlab-ci] Update debian-dev container version to 1.13

See merge request !18

1. remove scripts/ 2. add 'doc' target to smoke tests

See merge request !17

Also move setup.sh from scripts/ to tools/.

Use Dead Code Elimination (DCE) instead of #ifdef

See merge request !16

Add 'test' stage to CI

See merge request !15

This test fails for yet unknown reasons.

Add and apply clang-tidy

See merge request !14

remove unused dependencies.db left over from the deleted script dependencyManager.sh

See merge request !10

IWYU and license check

See merge request !13

smoke-test, clang-format, gitlab-ci

See merge request !12

Remove duplicate block()/unblock() code

See merge request !11

This makes all EMPER synchronization primitives inherit from
Blockable. As result all block and unblock operations of a context
will go to the same code path. We can later use this to store the set
of currently blocked contexts.

Also Blockable now inherits Logger, which makes some things easier,
but as result we have to invoke the logX() methods with "this->"
prepended. See related code comment.

fix Actor and UnboundedBlockingMpscQueue

See merge request !9

Currently the write to 'state' from stop() is overridden in actorLoop()
if it occurs while the Actor is executing the while loop body in actorLoop()
because the while loop body unconditionally writes 'state'.

To prevent those lost 'state' updates actorLoop() now uses compare_exchange
to switch 'state'.

Not initializing blockedContext means its original value is undefined and
probably some random stack value != nullptr.

If the first put() is executed before the first blocking get(), put() will read a
random value from blockedContext and will call unblock with this random context
pointer leading to execution of random memory.

declare die() as noreturn

See merge request !8

support generic test suites not just 'smoke'

See merge request !7

[meson] export and use meson options as C/C++ defines

See merge request !2

All options in meson_options.txt are exported in emper-config.h as
uppercase defines and prefixed with EMPER_.
Every source file using one of the EMPER_* defines now includes "emper-config.h".