message: build per default the target x86_64-unknown-hermit-kernel
  afterwards `cargo build` without any additional flag builds
  libhermit-rs for x86_64
diff: -#[target.x86_64-unknown-hermit-kernel]
  -#runner = "uhyve -v"
  +[unstable]
  +build-std = ["core", "alloc"]
  +
  +[build]
  +target = "x86_64-unknown-hermit-kernel"
  [target.x86_64-unknown-hermit-kernel]
  runner = "tests/hermit_test_runner.py"
  