prevent data races when initializing the workers PRNG seeds

See merge request !38

Each worker currently calls uniformIntDistribution(randomEngine)
which modifies the randomEngine internally and thus produces data races
when the threads run in parallel.

This change calls uniformIntDistribution(randomEngine) on the main thread
for each worker and passes the resulting seeds to the workerLoop.

The data race was found by gcc's tsan.

Add sanitizer CI targets

See merge request !35

Debugging changes

See merge request !37

To exclude debug code from release builds "if constexpr(emper::DEBUG)"
is preferred over "#ifndef NDEBUG".

Revert "[tests] don't undef NDEBUG for test executables"

See merge request !36

This reverts commit b33ac93c.

Now that logging is done independently from NDEBUG, we can re-enable
"undef NDEBUG for test executables". The rationale that we want to
undefine NDEBUG for test executable is that we want, even in release
builds, asserts in tests enabled. Note that this also applies to
asserts in the emper core library, if those are in *headers*.

use DIE* macros instead of the die function

See merge request !33

make logging configurable during compilation and runtime

See merge request !32

    Compile-time:
      * A new meson option 'log_level' is introduced which has all the values from the
        Loglevel enum
      * The 'OFF' option defines EMPER_LOG_OFF which causes the LOG* macros to be empty
        and the Logger<>::log function to return immediately
      * The default 'automatic' option sets 'log_level' to 'Error' for release builds
        and to 'ALL' otherwise

    Runtime:
      * The global variable emper::log_level defined in Debug.hpp controls the logging output
      * It is initialized with the meson option 'log_level' but can be changed during runtime

make the userspace-rcu dependency optional

See merge request !28

Disable the userpace-rcu support by default.
Our used userspace-rcu flavor memb is rather new and not available in
liburcu version 0.10 available in debian buster.
This change switches from using DCE and "if constexpr" to the C
preprocessor so the library is only needed when the userspace-rcu support
is actually enabled.

[gitlab-ci] Use flowdalic/debian-testing-dev:1.0 as container image

See merge request !34

And fix the #include issues reported by the newer IWYU version.

[UnboundedBlockingMpscQueue] Fix message loss

See merge request !31

Avoid messages getting lost in the queue.

use proper camel case for URCU test

See merge request !26

do not run tests in parallel by default

See merge request !27

[docs] rename doc target from speedymalloc to emper

See merge request !29

Remove -UNDEBUG from tests

See merge request !25

The explicit -UNDEBUG was introduced in the CMake to meson migration (62900cd1)
but as far as I can tell it was not present in the CMake tests definition.

It makes tests less reliable because it enables only some debug messages but not
all.
For example if emper is build with NDEBUG a test using a Semaphore
will output debug messages from the Semaphore but not from the Runtime.

[test] add AlarmActorTest

See merge request !24

register each worker thread for userspace RCU using the default flavor

See merge request i4/manycore/emper!23

Introduce a new Actor test using BinaryPrivateSemaphores and an Actor.
Multiple fibers are created which create a BPS on the stack, submit it to the actor
and wait on the semaphore.
The Actor simply signals each semaphore it receives.

The SimpleURCUTest creates a lock-less hash table and inserts values from
separate fibers and verifies the correct insertion.

The default flavor is the preferred way to use the userspace library it uses
the sys_membarrier syscall or falls back to using userspace membarriers.

This adds the liburcu dependency which must be installed regardless the
'liburcu' meson option.

Tests

See merge request !22