RISC-V: Fix fails of testcases

FAIL: gcc.target/riscv/rvv/autovec/vls-vlmax/vec_extract-run.c -std=c99 -O3 -ftree-vectorize --param riscv-autovec-preference=fixed-vlmax (test for excess errors)
Excess errors:
xgcc: fatal error: Cannot find suitable multilib set for '-march=rv64imafdcv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'/'-mabi=lp64d'
compilation terminated.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/vls-vlmax/vec_extract-run.c: Fix fail.
	* gcc.target/riscv/rvv/autovec/vls-vlmax/vec_extract-zvfh-run.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls-vlmax/vec_set-run.c: Ditto.
	* gcc.target/riscv/rvv/autovec/vls-vlmax/vec_set-zvfh-run.c: Ditto.