cmd/gc: fix filename output format verb for -s

%lL will prepend the current directory to the filename, which is not
what we want here (as the file name is already absolute).

Fixes #9150.

Change-Id: I4c9386be6baf421393b92d9401a264b4692986d0
Reviewed-on: https://go-review.googlesource.com/2231Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/gc/typecheck.c

@@ -2537,7 +2537,7 @@ pushtype(Node *n, Type *t)
 	else if(debug['s']) {
 		typecheck(&n->right, Etype);
 		if(n->right->type != T && eqtype(n->right->type, t))
-			print("%lL: redundant type: %T\n", n->lineno, t);
+			print("%L: redundant type: %T\n", n->lineno, t);
 	}
 }