Vendor dependencies for 0.3.0 release

vendor/bindgen/extra_assertions.rs

@@ -0,0 +1,17 @@
+//! Macros for defining extra assertions that should only be checked in testing
+//! and/or CI when the `__testing_only_extra_assertions` feature is enabled.
+
+/// Simple macro that forwards to assert! when using
+/// `__testing_only_extra_assertions`.
+macro_rules! extra_assert {
+    ( $cond:expr ) => {
+        if cfg!(feature = "__testing_only_extra_assertions") {
+            assert!($cond);
+        }
+    };
+    ( $cond:expr , $( $arg:tt )+ ) => {
+        if cfg!(feature = "__testing_only_extra_assertions") {
+            assert!($cond, $( $arg )* )
+        }
+    };
+}