Anyone have an idea what causes this:
```
  = note: rust-lld: error: undefined symbol: _critical_section_1_0_acquire
          >>> referenced by lib.rs:202 (/Users/egger/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/critical-section-1.2.0/src/lib.rs:202)
          >>>               /Users/egger/OSS/stm32f0xx-hal/target/thumbv6m-none-eabi/release/examples/i2c_find_address-02979d0a1ca89bad.i2c_find_address.2d5770c8a10955a3-cgu.0.rcgu.o:(_defmt_acquire)
```