RISC-V: Add conditional autovec convert(INT<->INT) patterns

RISC-V: Add conditional autovec convert(INT<->INT) patterns

gcc/ChangeLog:

	* config/riscv/autovec-opt.md (*cond_<optab><v_double_trunc><mode>):
	New combine pattern.
	(*cond_<optab><v_quad_trunc><mode>): Ditto.
	(*cond_<optab><v_oct_trunc><mode>): Ditto.
	(*cond_trunc<mode><v_double_trunc>): Ditto.
	* config/riscv/autovec.md (<optab><v_quad_trunc><mode>2): Adjust.
	(<optab><v_oct_trunc><mode>2): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/binop/narrow-3.c: Adjust.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-1.h: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-2.h: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-rv32-1.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-rv32-2.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-rv64-1.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int-rv64-2.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int_run-1.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/cond_convert_int2int_run-2.c: New test.