RISC-V: testsuite: Fix vx_vf_*run-1-f16.c run tests.

RISC-V: testsuite: Fix vx_vf_*run-1-f16.c run tests.

This patch fixes the vf_vfmacc-run-1-f16.c test failures on rv32
by adding zvfh requirements as well as options to the test and
the target harness.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmacc-run-1-f16.c:
	Add zvfh requirements and options.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmadd-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmsac-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmsub-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmacc-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmadd-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmsac-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmsub-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfwmacc-run-1-f16.c:
	Ditto.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfwmsac-run-1-f16.c:
	Ditto.
	* lib/target-supports.exp: Add zvfh options.