Give ConfigToolDependency() a finish_init callback, so that tool-specific
initialization can be called from the constructor, rather than after
construction in the factory class.
v2:
finalize -> finish_init for clarity
find_external_dependency() now makes and iterates over a list of callables
which are constructors with bound arguments for the dependency objects we
are going to attempt to make, so we can consolidate reporting on these
attempts and handling failures in that function.
We now pass the current subproject to every FeatureNew and
FeatureDeprecated call. This requires a bunch of rework to:
1. Ensure that we have access to the subproject in the list of
arguments when used as a decorator (see _get_callee_args).
2. Pass the subproject to .use() when it's called manually.
3. We also can't do feature checks for new features in
meson_options.txt because that's parsed before we know the
meson_version from project()
D is not a 'c-like' language, but it can link to C libraries. The same
might be true of Rust in the future and Go when we add support for it.
This contains no functionality changes.
All dependencies were using find_library, has_header, get_define, etc on
self.compiler assuming that it's a compiler that outputs and consumes
C-like libraries. This is not true for D (and in the future, for Rust)
since although they can consume C libraries, they do not use the
C ecosystem.
For such purposes, we now have self.clib_compiler. Nothing uses
self.compiler anymore as a result, and it has been removed.
Since this is only consulted while constructing the Dependency object, it's
result doesn't depend on the instance (and it would make no sense if it did)