RISC-V: Add support for XCVmem extension in CV32E40P

Spec: https://docs.openhwgroup.org/projects/cv32e40p-user-manual/en/latest/instruction_set_extensions.html

Contributors:
  Mary Bennett <mary.bennett@embecosm.com>
  Nandni Jamnadas <nandni.jamnadas@embecosm.com>
  Pietra Ferreira <pietra.ferreira@embecosm.com>
  Charlie Keaney
  Jessica Mills
  Craig Blackmore <craig.blackmore@embecosm.com>
  Simon Cook <simon.cook@embecosm.com>
  Jeremy Bennett <jeremy.bennett@embecosm.com>
  Helene Chelin <helene.chelin@embecosm.com>

bfd/ChangeLog:
	* elfxx-riscv.c (riscv_multi_subset_supports): Add `xcvmem`
          instruction class.
	(riscv_multi_subset_supports_ext): Likewise.

gas/ChangeLog:
	* doc/c-riscv.texi: Note XCVmem as an additional ISA extension
          for CORE-V.
	* testsuite/gas/riscv/cv-mem-fail-march.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-march.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-march.s: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-01.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-01.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-01.s: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-02.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-02.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-02.s: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-03.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-03.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-03.s: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-04.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-04.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-04.s: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-05.d: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-05.l: New test.
	* testsuite/gas/riscv/cv-mem-fail-operand-05.s: New test.
	* testsuite/gas/riscv/cv-mem-lbpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lbpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lbrr.d: New test.
	* testsuite/gas/riscv/cv-mem-lbrr.s: New test.
	* testsuite/gas/riscv/cv-mem-lbrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lbrrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lbupost.d: New test.
	* testsuite/gas/riscv/cv-mem-lbupost.s: New test.
	* testsuite/gas/riscv/cv-mem-lburr.d: New test.
	* testsuite/gas/riscv/cv-mem-lburr.s: New test.
	* testsuite/gas/riscv/cv-mem-lburrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lburrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lhpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lhpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lhrr.d: New test.
	* testsuite/gas/riscv/cv-mem-lhrr.s: New test.
	* testsuite/gas/riscv/cv-mem-lhrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lhrrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lhupost.d: New test.
	* testsuite/gas/riscv/cv-mem-lhupost.s: New test.
	* testsuite/gas/riscv/cv-mem-lhurr.d: New test.
	* testsuite/gas/riscv/cv-mem-lhurr.s: New test.
	* testsuite/gas/riscv/cv-mem-lhurrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lhurrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lwpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lwpost.s: New test.
	* testsuite/gas/riscv/cv-mem-lwrr.d: New test.
	* testsuite/gas/riscv/cv-mem-lwrr.s: New test.
	* testsuite/gas/riscv/cv-mem-lwrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-lwrrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-sbpost.d: New test.
	* testsuite/gas/riscv/cv-mem-sbpost.s: New test.
	* testsuite/gas/riscv/cv-mem-sbrr.d: New test.
	* testsuite/gas/riscv/cv-mem-sbrr.s: New test.
	* testsuite/gas/riscv/cv-mem-sbrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-sbrrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-shpost.d: New test.
	* testsuite/gas/riscv/cv-mem-shpost.s: New test.
	* testsuite/gas/riscv/cv-mem-shrr.d: New test.
	* testsuite/gas/riscv/cv-mem-shrr.s: New test.
	* testsuite/gas/riscv/cv-mem-shrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-shrrpost.s: New test.
	* testsuite/gas/riscv/cv-mem-swpost.d: New test.
	* testsuite/gas/riscv/cv-mem-swpost.s: New test.
	* testsuite/gas/riscv/cv-mem-swrr.d: New test.
	* testsuite/gas/riscv/cv-mem-swrr.s: New test.
	* testsuite/gas/riscv/cv-mem-swrrpost.d: New test.
	* testsuite/gas/riscv/cv-mem-swrrpost.s: New test.

include/ChangeLog:
	* opcode/riscv-opc.h: Add corresponding MATCH and MASK macros
          for XCVmem.
	* opcode/riscv.h: Add corresponding EXTRACT and ENCODE macros
          for XCVmem.
	(enum riscv_insn_class): Add the XCVmem instruction class.

opcodes/ChangeLog:
	* riscv-opc.c: Add XCVmem instructions.