Lowercase the "wrong type in main fn" error

src/comp/middle/typeck.rs

@@ -2681,7 +2681,7 @@ fn check_main_fn_ty(tcx: &ty::ctxt, main_id: &ast::node_id) {
         ok &=
             num_args == 0u || num_args == 1u && arg_is_argv_ty(tcx, args.(0));
         if !ok {
-            tcx.sess.err("Wrong type in main function: found " +
+            tcx.sess.err("wrong type in main function: found " +
                              ty_to_str(tcx, main_t));
         }
       }

src/test/compile-fail/bad-main.rs

@@ -1,3 +1,3 @@
-// error-pattern:Wrong type in main function
+// error-pattern:wrong type in main function
 
 fn main(x: int) { }

src/test/compile-fail/main-wrong-type-2.rs

@@ -1,2 +1,2 @@
-// error-pattern:Wrong type in main function: found fn() -> char
+// error-pattern:wrong type in main function: found fn() -> char
 fn main() -> char { }

src/test/compile-fail/main-wrong-type.rs

@@ -1,2 +1,2 @@
-// error-pattern:Wrong type in main function: found fn(
+// error-pattern:wrong type in main function: found fn(
 fn main(foo: {x: int, y: int}) { }