Macro bootstrap_tool

macro_rules! bootstrap_tool {
    ($(
        $name:ident, $path:expr, $tool_name:expr
        $(,is_external_tool = $external:expr)*
        $(,is_unstable_tool = $unstable:expr)*
        $(,allow_features = $allow_features:expr)?
        $(,submodules = $submodules:expr)?
        ;
    )+) => { ... };
}