Hi,

This patch adds support for MVE instructions VSHRNT, VSHRNB, VRSHRNT, 
VRSHRNB, VQSHRUNT, VQSHRUNT, VQRSHRNT, VQRSHRNB, VQRSHRUNT, and VQRSHRUNB.

gas/ChangeLog:

2019-05-01  Andre Vieira  <andre.simoesdiasvieira@arm.com>

	* config/tc-arm.c (M_MNEM_vshrnt, M_MNEM_vshrnb, M_MNEM_vrshrnt,
         M_MNEM_vqshrnt, M_MNEM_vqshrnb, M_MNEM_vqshrunt, M_MNEM_vqshrunb,
         M_MNEM_vrshrnb, M_MNEM_vqrshrnt, M_MNEM_vqrshrnb, M_MNEM_vqrshrunt,
         M_MNEM_vqrshrunb): New instruction encodings.
	(do_mve_vshrn): New encoding function.
         (insns): Add entries for MVE mnemonics.
	* testsuite/gas/arm/mve-vqrshrn-bad.d: New test.
	* testsuite/gas/arm/mve-vqrshrn-bad.l: New test.
	* testsuite/gas/arm/mve-vqrshrn-bad.s: New test.
	* testsuite/gas/arm/mve-vshrn-bad.d: New test.
	* testsuite/gas/arm/mve-vshrn-bad.l: New test.
	* testsuite/gas/arm/mve-vshrn-bad.s: New test.