Broken gcc

In #9, @kotborealis added a `gcc` command, but this doesn't quite work with arbitrary files.
For example:
```console
$ cat README.md | wc -l
44

$ gcc -E -P -xc README.md | wc -l
README.md:1:3: error: invalid preprocessing directive #cat
    1 | # cat(1) golf
      |   ^~~
35
```
While it's an interesting hack, I don't think it belongs in the "Pure league".