feat(tests): add tests for rustbindgen annotations

Author: rich-ayr

bindgen-tests/tests/expectations/tests/attribute-custom.rs

@@ -12,4 +12,4 @@ union foo_union {
 struct non_matching {
     int inner;
 };
-int foo_function() { return 1; }
+int foo_function() { return 1; }

bindgen-tests/tests/headers/attribute-custom-cli.h

@@ -26,3 +26,8 @@ struct my_type2 {
 struct my_type3 {
     unsigned long a;
 };
+
+/**
+ * <div rustbindgen attribute="#[must_use]" attribute="#[doc(hidden)]"></div>
+ */
+int function_attributes() { return 1; }