Split out tests (and parts of tests) which require a native compiler
from the 'common' suite to a new suite called 'native', so we can
selectively avoid running those tests when only a cross-compiler is
available.
Also move test '211 cmake module' to 'cmake' suite, since it appears
that the way we use cmake requires a native compiler.
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
Fortran: check for undeclared variables by forcing implicit none everywhere
C/C++: check for unused parameters and return types
removed unused variables from test cases
ci: do missing return and unused arg check with Github Actions