Fix the encoding of the MSP430's RRUX instruction.

Fix the encoding of the MSP430's RRUX instruction.

	PR target/19561
opcdoe	* msp430-dis.c (print_insn_msp430): Add a special case for
	decoding an RRC instruction with the ZC bit set in the extension
	word.

include	* opcode/msp430.h (IGNORE_CARRY_BIT): New define.
	(RRUX): Synthesise using case 2 rather than 7.

gas	* config/tc-msp430.c (msp430_operands): Remove case 7.  Use case 2
	to handle encoding of RRUX instruction.
	* testsuite/gas/msp430/msp430x.s: Add more tests of the extended
	shift instructions.
	* testsuite/gas/msp430/msp430x.d: Update expected disassembly.