Right now sub-sub projects are not correctly registered, because we
don't have a way to pass up past the first level of subproject. This
patch changes that by making the build_Def_files as defined in the
Interpreter initializer accurate for translated dependencies, ie, cmake
dependencies won't define a dependency on a non-existent meson.build.
This means that it can always add the subi.build_def_files because they
are always accurate.

It used to ignore the required argument and got fixed to be consistent
with dependency() function.

Currently if you change the `choices` field in the meson_options.txt
file, no update will be done until `meson setup --wipe` is called. Now
if the choices change then the options will be properly merged.

If the currently select value is still valid it is guaranteed to be
kept, if it is now invalid the new default value will be used and a
warning will be printed.

Fixes #7386

`pathlib.Path.glob()` also returns directories that match source
filenames (i.e. a directory named `test.h/`), but `clang-format` and
`clang-tidy` fail when handed a directory. We manually skip calling
`clang-format` and `clang-tidy` on those directories.

Handle add_languages(native:) in introspector

If the meson.build doesn't use a native compiler, the native compiler
options (e.g. 'c_args') shouldn't be present in the output of 'meson
introspect --buildoptions'.

Something like {a: foo} currently stymies the IntrospectionInterpreter and
breaks introspection of the source directory.  The fix is just to walk the keys
and return a dummy dictionary.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>