Some CMake packages fail to find at all if no version is specified.
This commit adds a cmake_version parameter to dependency() to allow you
to specify the requested version.
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