Use local_inner_macros to resolve assert_matches! within $crate

[yvt]

This fixes errors when using debug_assert_matches! via Rust 2018 style macro imports like use assert_matches::debug_assert_matches;.

error: cannot find macro `assert_matches` in this scope
   --> redacted.rs:573:5
    |
573 | /     debug_assert_matches!(
574 | |         task.st.read(&*lock),
575 | |         (task::TaskSt::Running | task::TaskSt::Waiting)
576 | |     );
    | |______^
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

Related issue: rust-lang-nursery/lazy-static.rs#107

[zertosh]

@murarth, can you please publish a release with this?

[murarth]

Just published version 1.5.0