Only benchmark the lib target for crates.io

Author: Mark-Simulacrum

collector/benchmarks/crates.io/makefile

@@ -1,8 +1,9 @@
 .PHONY: all
 
 # at commit ef1ac581f9c4ea6a906347d43776418acfdbb8ca
+# We must only benchmark the lib target because otherwise we can't pass args with CARGO_RUSTC_OPTS
 
 all:
-	$(CARGO) rustc $(CARGO_OPTS) -- $(CARGO_RUSTC_OPTS)
+	$(CARGO) rustc $(CARGO_OPTS) --lib -- $(CARGO_RUSTC_OPTS)
 patches:
 	@echo ''