check denying warnings

Author: pvdrz

ci/test.sh

@@ -126,7 +126,7 @@ fi
 CARGO_ARGS=`get_cargo_args`
 
 # Ensure we build without warnings
-(cd bindgen-tests && cargo rustc --lib $CARGO_ARGS -- -Dwarnings)
+RUSTFLAGS="-Dwarnings" cargo check
 
 if [ "$BINDGEN_MAIN_TESTS" == "1" ]; then
   # Run the tests