[PATCH] RISC-V: Enable zvfh for vector-scalar half-float run tests

[PATCH] RISC-V: Enable zvfh for vector-scalar half-float run tests

zvfh is not enabled at the testsuite level. It has to be enabled on a testcase
by testcase basis. This was correctly done for compile tests but not for run
tests. This patch fixes it.
Also, to ensure correct results with half-precision floats, MAX_RELATIVE_DIFF is
set according to the type.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vx_vf/vf_mulop_run.h: Set
	MAX_RELATIVE_DIFF depending on type.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmacc-run-1-f16.c: Enable zvfh.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmadd-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmsac-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfmsub-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmacc-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmadd-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmsac-run-1-f16.c: Likewise.
	* gcc.target/riscv/rvv/autovec/vx_vf/vf_vfnmsub-run-1-f16.c: Likewise.