Simplify return & fshut() logic

Get rid of the !!()-constructs and use ret where available (or introduce it).

In some cases, there would be an "abort" on the first fshut-error, but we want
to close all files and report all warnings and then quit, not just the warning
for the first file.

expr.c

@@ -258,8 +258,11 @@ main(int argc, char *argv[])
 	int ret;
 
 	argv0 = argv[0], argc--, argv++;
+
 	ret = !parse(argv, argc);
-	enfshut(3, stdout, "<stdout>");
+
+	if (fshut(stdout, "<stdout>"))
+		ret = 3;
 
 	return ret;
 }