Fix address violation problems when disassembling a corrupt RX binary.

Fix address violation problems when disassembling a corrupt RX binary.

	PR binutils/21587
	* rx-decode.opc: Include libiberty.h
	(GET_SCALE): New macro - validates access to SCALE array.
	(GET_PSCALE): New macro - validates access to PSCALE array.
	(DIs, SIs, S2Is, rx_disp): Use new macros.
	* rx-decode.c: Regenerate.