RISC-V: Use RV64 mcmodel=medany multilibs when mcmodel is not specified

This commit updates the multilib configurations such that the multilibs
that are built for the `medany` code model are used when the `mcmodel`
flag is not explicitly specified (i.e. when `medlow` code model is in
use).

Note that the multilibs compiled with the `medany` code model can be
used with the application code compiled with the `medlow` code model.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

Author: stephanosio

gcc/config/riscv/t-zephyr

@@ -91,15 +91,31 @@ march.rv32e_zicsr_zifencei/mabi.ilp32e=march.rv32ec_zicsr_zifencei/mabi.ilp32e \
 march.rv32em_zicsr_zifencei/mabi.ilp32e=march.rv32ema_zicsr_zifencei/mabi.ilp32e \
 march.rv32emc_zicsr_zifencei/mabi.ilp32e=march.rv32emac_zicsr_zifencei/mabi.ilp32e \
 march.rv32emc_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.ilp32e=march.rv32emac_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.ilp32e \
+march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64i_zicsr_zifencei/mabi.lp64 \
+march.rv64im_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64im_zicsr_zifencei/mabi.lp64 \
+march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64 \
+march.rv64imac_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64imac_zicsr_zifencei/mabi.lp64 \
+march.rv64imac_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64imac_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64 \
+march.rv64imafdc_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64imafdc_zicsr_zifencei/mabi.lp64d \
+march.rv64imafd_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64imafd_zicsr_zifencei/mabi.lp64d \
 march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ia_zicsr_zifencei/mabi.lp64/mcmodel.medany \
+march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ia_zicsr_zifencei/mabi.lp64 \
 march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64iac_zicsr_zifencei/mabi.lp64/mcmodel.medany \
+march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64iac_zicsr_zifencei/mabi.lp64 \
 march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ic_zicsr_zifencei/mabi.lp64/mcmodel.medany \
+march.rv64i_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ic_zicsr_zifencei/mabi.lp64 \
 march.rv64im_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ima_zicsr_zifencei/mabi.lp64/mcmodel.medany \
+march.rv64im_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64ima_zicsr_zifencei/mabi.lp64 \
 march.rv64im_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64imc_zicsr_zifencei/mabi.lp64/mcmodel.medany \
+march.rv64im_zicsr_zifencei/mabi.lp64/mcmodel.medany=march.rv64imc_zicsr_zifencei/mabi.lp64 \
 march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64ima_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany \
+march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64ima_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64 \
 march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64imc_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany \
+march.rv64im_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64/mcmodel.medany=march.rv64imc_zicsr_zifencei_zba_zbb_zbc_zbs/mabi.lp64 \
 march.rv64imafdc_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64gc/mabi.lp64d/mcmodel.medany \
-march.rv64imafd_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64g/mabi.lp64d/mcmodel.medany
+march.rv64imafdc_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64gc/mabi.lp64d \
+march.rv64imafd_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64g/mabi.lp64d/mcmodel.medany \
+march.rv64imafd_zicsr_zifencei/mabi.lp64d/mcmodel.medany=march.rv64g/mabi.lp64d
 
 # Automatically generate multilib options and directory names from the target configurations
 space := $(subst ,, )