RISC-V: Add missing conversion tests.

RISC-V: Add missing conversion tests.

This adds some missing tests for vf[nw]cvt.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-ftoi-run.c:
	Add tests.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-ftoi-rv32gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-ftoi-rv64gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-ftoi-template.h:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-itof-rv32gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-itof-rv64gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-itof-template.h:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfncvt-itof-zvfh-run.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-ftoi-rv32gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-ftoi-rv64gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-ftoi-template.h:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-ftoi-zvfh-run.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-itof-run.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-itof-rv32gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-itof-rv64gcv.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-itof-template.h:
	Ditto.
	* gcc.target/riscv/rvv/autovec/conversions/vfwcvt-itof-zvfh-run.c:
	Ditto.