zephyr modules: add 'snippet_root' support to module.yml

This key may appear in a module.yml's 'settings' map, and works
analogously to the already existing 'board_root', 'dts_root', etc.
keys: if set, its value is interpreted as a directory that will be
added to SNIPPET ROOT.

For example, if a module.yml contains:

  settings:
    snippet_root: foo

Then 'foo', relative to the module's base directory, will be added to
SNIPPET_ROOT. This then means that any snippets in foo/snippets will
be discovered by the build system.

Signed-off-by: Marti Bolivar <marti.bolivar@nordicsemi.no>
1 file changed