cmd/gc: drop { } around single-line if-statement body

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/85890043

src/cmd/gc/gen.c

@@ -301,9 +301,8 @@ gen(Node *n)
 		break;
 
 	case OLABEL:
-		if(isblanksym(n->left->sym)) {
+		if(isblanksym(n->left->sym))
 			break;
-		}
 		
 		lab = newlab(n);