Add integration test for lib injection

tests/mybin/src/main.rs

@@ -0,0 +1,12 @@
+#[link(name = "mylib", kind = "dylib")]
+extern {
+	fn mylib_foo() -> u8;
+	fn mylib_bar() -> u8;
+}
+
+fn main() {
+	println!("Hello, world!");
+
+	assert_eq!(unsafe { mylib_bar() }, 100);
+	std::process::exit(unsafe { mylib_foo() } as i32);
+}