RISC-V: Add unary C/C++ API support

RISC-V: Add unary C/C++ API support

gcc/ChangeLog:

	* config/riscv/iterators.md: Add neg and not.
	* config/riscv/riscv-vector-builtins-bases.cc (class unop): New class.
	(BASE): Ditto.
	* config/riscv/riscv-vector-builtins-bases.h: Ditto.
	* config/riscv/riscv-vector-builtins-functions.def (vadd): Rename binop
	into alu.
	(vsub): Ditto.
	(vand): Ditto.
	(vor): Ditto.
	(vxor): Ditto.
	(vsll): Ditto.
	(vsra): Ditto.
	(vsrl): Ditto.
	(vmin): Ditto.
	(vmax): Ditto.
	(vminu): Ditto.
	(vmaxu): Ditto.
	(vmul): Ditto.
	(vdiv): Ditto.
	(vrem): Ditto.
	(vdivu): Ditto.
	(vremu): Ditto.
	(vrsub): Ditto.
	(vneg): Ditto.
	(vnot): Ditto.
	* config/riscv/riscv-vector-builtins-shapes.cc (struct binop_def): Ditto.
	(struct alu_def): Ditto.
	(SHAPE): Ditto.
	* config/riscv/riscv-vector-builtins-shapes.h: Ditto.
	* config/riscv/riscv-vector-builtins.cc: Support unary C/C/++.
	* config/riscv/vector-iterators.md: New iterator.
	* config/riscv/vector.md (@pred_<optab><mode>): New pattern