riscv: add riscv arch support

[Jer6y]

add riscv arch support

Why does using -O0 result in fewer test case failures compared to using -O2 on openEuler RISCV? I am not certain of the reason, but it may be related to some issues with the compiler optimizations.

The porting effectiveness test can be found at the link https://github.com/Jer6y/rv_linux_bug, which also describes a bug related to ptrace on RISCV Linux that has not yet been fixed. However, it is possible to perform some rather rudimentary operations locally to temporarily correct the ptrace issue.

#368