GCC version check.

Created by: corentinmaraisT

Switch to gcc 13. Implementation of a new argument isa_extension in cva6.py to choose additional extensions. From version 11.1.0, some instructions are not anymore included in the global computation. The isa must have two extensions enabled to include the removed instructions : zicsr and zifencei. isa_extension is set by default on these two extensions.

python3 cva6.py --testlist=../tests/testlist_riscv-compliance-cv32a60x.yaml --test rv32i-I-ADD-01 --iss_yaml cva6.yaml --target cv32a60x --iss= –isa_extension=zbb

In the above example, zbb is added to the two instructions set by default.

No version prior to 11.1.0 will be supported after this mofdification.