19634: tree-wide: mixed box of compilation fixes with clang r=benpicco a=maribu
### Contribution description
As the title says: This should increase the number of apps being able to build with clang quite a bit.
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@posteo.net>
This allows including C headers from C++. It sadly reduced the
diagnostics on C++ code as well, were there warning may make sense as
unintended side effect. We may be able to drop that later on, when more
C APIs are properly wrapped in native C++ APIs, so that C headers do no
longer need to be compatible with C++ compilers.
When support for this package was introduced printf calls inside the
uwb-core where bloating stack usage, but this is no longer the case,
so prefere lower stack usage.
As nRF9160 doesn't have a bluetooth radio, we should not pull the same dependencies as nRF52, thus ensure these dependencies are only added for nrf5x families
