Add CARGO_INCREMENTAL=0 to work around clippy 1.72 bug (#938)

This PR works around the issue
#929, using the suggestion in
rust-lang/rust#83085 (comment).

.github/scripts/ci-style.sh

@@ -2,6 +2,13 @@
 
 export RUSTFLAGS="-D warnings -A unknown-lints"
 
+# Workaround the clippy issue on Rust 1.72: https://github.com/mmtk/mmtk-core/issues/929.
+# If we are not testing with Rust 1.72, or there is no problem running the following clippy checks, we can remove this export.
+CLIPPY_VERSION=$(cargo clippy --version)
+if [[ $CLIPPY_VERSION == "clippy 0.1.72"* ]]; then
+    export CARGO_INCREMENTAL=0
+fi
+
 # --- Check main crate ---
 
 # check base

src/util/metadata/side_metadata/spec_defs.rs

@@ -100,6 +100,9 @@ define_side_metadata_specs!(
 
 #[cfg(test)]
 mod tests {
+    // We assert on constants to test if the macro is working properly.
+    #![allow(clippy::assertions_on_constants)]
+
     use super::*;
     #[test]
     fn first_global_spec() {