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
cmake: get language from Meson project if not specified as depedency(..., langugage: ...)
deps: add threads method:cmake
dependency('threads', method: 'cmake') is useful for cmake unit tests
or those who just want to find threads using cmake.
cmake: project(... Fortran) generally also requires C language
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