RISC-V: Add support for the Zvbc extension

RISC-V: Add support for the Zvbc extension

Zvbc is part of the crypto vector extensions.

This extension adds the following instructions:
- vclmul.[vv,vx]
- vclmulh.[vv,vx]

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_multi_subset_supports): Add instruction
	class support for Zvbc.
	(riscv_multi_subset_supports_ext): Likewise.

gas/ChangeLog:

	* testsuite/gas/riscv/zvbc.d: New test.
	* testsuite/gas/riscv/zvbc.s: New test.

include/ChangeLog:

	* opcode/riscv-opc.h (MATCH_VCLMUL_VV): New.
	(MASK_VCLMUL_VV): New.
	(MATCH_VCLMUL_VX): New.
	(MASK_VCLMUL_VX): New.
	(MATCH_VCLMULH_VV): New.
	(MASK_VCLMULH_VV): New.
	(MATCH_VCLMULH_VX): New.
	(MASK_VCLMULH_VX): New.
	(DECLARE_INSN): New.
	* opcode/riscv.h (enum riscv_insn_class): Add instruction class
	  support for Zvbc.

opcodes/ChangeLog:

	* riscv-opc.c: Add Zvbc instruction.

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>