This makes rtt output work right when using `cargo run` in release mode.
Debug was already enabled for release builds in some of the examples but
not all.
- probe-run screwed up the last release 2 weeks ago and it's still not fixed (issue 391). Doesn't look well maintained.
- Even when it's not broken, it lags behind probe-rs-cli in new chips support because it's slow in updating probe-rs.
inline assembly is supported since rust 1.59, we're way past that.
enabling this makes the compiled code more compact, and on rp2040
even decreses memory usage by not needing thunks in sram.
This introduces a `Pender` struct with enum cases for thread-mode, interrupt-mode and
custom callback executors. This avoids calls through function pointers when using only
the thread or interrupt executors. Faster, and friendlier to `cargo-call-stack`.
`embassy-executor` now has `arch-xxx` Cargo features to select the arch and to enable
the builtin executors (thread and interrupt).
