`BOX64_DYNAREC_TEST` on RISC-V is Failing
### Description

I used `BOX64_DYNAREC_TEST` to test box64. And I saw that box64 must have some issues about this flag on RISC-V (it is good on ARM though). Many crashes I met, seems that RISC-V `BOX64_DYNAREC_TEST` cannot correctly handle the programs with PLT Callings. A hello-world program can reproduce the issue.

```console
$ cat hello.c
#include <stdio.h>

int main() {
    puts("Hello World");
    return 0;
}
$ x86_64-linux-gnu-gcc hello.c -o hello
$ BOX64_DYNAREC_TEST=1 box64 ./hello  # here `box64` is running on risc-v.
(( !crash! ))
```

Due to this issue, I cannot move my work forward nearly at all. _Hope we can solve this issue as soon as possible..._