rustc_codegen_gcc: fix changed method signature

Author: durin42

src/lib.rs

@@ -418,7 +418,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         back::write::codegen(cgcx, dcx, module, config)
     }
 
-    fn prepare_thin(_module: ModuleCodegen<Self::Module>) -> (String, Self::ThinBuffer) {
+    fn prepare_thin(_module: ModuleCodegen<Self::Module>, _emit_summary: bool) -> (String, Self::ThinBuffer) {
         unimplemented!();
     }