[PATCH v4 1/2] RISC-V: Add support for XCVmac extension in CV32E40P

Spec: github.com/openhwgroup/core-v-sw/blob/master/specifications/corev-builtin-spec.md

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>

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc: Add XCVmac.
	* config/riscv/riscv-ftypes.def: Add XCVmac builtins.
	* config/riscv/riscv-builtins.cc: Likewise.
	* config/riscv/riscv.md: Likewise.
	* config/riscv/riscv.opt: Likewise.
	* doc/extend.texi: Add XCVmac builtin documentation.
	* doc/sourcebuild.texi: Likewise.
	* config/riscv/corev.def: New file.
	* config/riscv/corev.md: New file.

gcc/testsuite/ChangeLog:

	* lib/target-supports.exp: Add new effective target check.
	* gcc.target/riscv/cv-mac-compile.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mac.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-machhsn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-machhsrn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-machhun.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-machhurn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-macsn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-macsrn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-macun.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-macurn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-msu.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulhhsn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulhhsrn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulhhun.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulhhurn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulsn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulsrn.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulun.c: New test.
	* gcc.target/riscv/cv-mac-fail-compile-mulurn.c: New test.
	* gcc.target/riscv/cv-mac-test-autogeneration.c: New test.