add rp6502 target

libsrc/rp6502/codepage.c

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2023 Rumbledethumps
+ *
+ * SPDX-License-Identifier: Zlib
+ * SPDX-License-Identifier: BSD-3-Clause
+ * SPDX-License-Identifier: Unlicense
+ */
+
+#include <rp6502.h>
+
+int __fastcall__ codepage(void)
+{
+    return ria_call_int(RIA_OP_CODEPAGE);
+}