[core] Move Arduino flags to arduino-common

platform/common/fixups/WCharacterFixup.h

@@ -0,0 +1,17 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-04-23. */
+
+/* WCharacter.h uses deprecated isascii() and toascii(),
+   which are available in gnu++11 but not c++11 */
+#include <cstddef>
+
+#ifdef __STRICT_ANSI__
+
+inline bool isascii(int c) {
+  return ((c & ~0x7f) != 0 ? false : true);
+}
+
+inline bool toascii(int c) {
+  return (c & 0x7f);
+}
+
+#endif