ci: configure cargo-all-features

Skip explicitly adding optional dependencies to the permutation matrix
(e.g. for example testing with --no-default-features, but the
vmm-sys-util optional dependency enabled anyway), as this does not seem
very useful (there is no way for a downstream to ever actually use this
configuration).

Signed-off-by: Patrick Roy <roypat@amazon.co.uk>

Author: roypat

.buildkite/custom-tests.json

@@ -4,14 +4,6 @@
       "test_name": "miri",
       "command": "RUST_BACKTRACE=1 MIRIFLAGS='-Zmiri-disable-isolation -Zmiri-backtrace=full' cargo +nightly miri test --features backend-mmap,backend-bitmap",
       "platform": ["x86_64", "aarch64"]
-    },
-    {
-      "test_name": "clippy-no-xen",
-      "command": "cargo clippy --workspace --bins --examples --benches  --features 'backend-bitmap backend-mmap backend-atomic' --all-targets -- -D warnings -D clippy::undocumented_unsafe_blocks",
-      "platform": [
-        "x86_64",
-        "aarch64"
-      ]
     }
   ]
 }

Cargo.toml

@@ -47,3 +47,6 @@ codegen-units = 1
 [package.metadata.docs.rs]
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[package.metadata.cargo-all-features]
+skip_optional_dependencies = true