fix fputwc return value

src/stdio/fputwc.c

@@ -25,7 +25,7 @@ wint_t fputwc(wchar_t c, FILE *f)
 	FLOCK(f);
 	c = __fputwc_unlocked(c, f);
 	FUNLOCK(f);
-	return 0;
+	return c;
 }
 
 weak_alias(__fputwc_unlocked, fputwc_unlocked);