ldso: make exit condition clearer in fixup_rpath

breaking out of the switch-case when l==-1 means the conditional below
will necessarily be true (-1 >= buf_size, a size_t variable) and the
function will return 0. it is, however, somewhat unclear that that's
what's happening. simply returning there is simpler

ldso/dynlink.c

@@ -886,7 +886,7 @@ static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
 		case ENOENT:
 		case ENOTDIR:
 		case EACCES:
-			break;
+			return 0;
 		default:
 			return -1;
 		}