Add `-fstack-protector` support to wasi-libc (#351)

Add `-fstack-protector` support to wasi-libc (#351)

Inlcude `__stack_chk_fail.c` and initialize `__stack_chk_guard` in ctor.

```
$ cat main.c
char input[] = "0123456789012345";
int main(void) {
    char buf[8];

    for (char *sp = input, *dp = buf; *sp != '\0'; sp++, dp++) {
        *dp = *sp;
    }
    return 0;
}

$ clang main.c -fstack-protector
$ wasmtime ./a.out
Error: failed to run main module `./a.out`

Caused by:
    0: failed to invoke command default
    1: wasm trap: wasm `unreachable` instruction executed
       wasm backtrace:
           0:  0x258 - <unknown>!__stack_chk_fail
           1:  0x21e - <unknown>!__original_main
           2:   0xca - <unknown>!_start
```