compile asm code cause vtcc crash

a test code:

bug.c
```c
void main() {
        __asm__ __volatile__ ("pause");
        __atomic_thread_fence(0);
}
```

this can be compiled with `tcc`,

but when compile with `vtcc`:

```sh
$ ./vtcc bug.c
7ffda13c8040 : at ???: invalid memory access
```

Found by a PR at [https://github.com/vlang/v/pull/24788](url)