Add RanlibFailure

compiler/rustc_codegen_gcc/src/errors.rs

@@ -0,0 +1,7 @@
+use rustc_macros::SessionDiagnostic;
+
+#[derive(SessionDiagnostic)]
+#[diag(codegen_gcc::ranlib_failure)]
+pub(crate) struct RanlibFailure {
+    pub exit_code: Option<i32>
+}