pyconfig.h string values are double-quoted in sysconfigdat

# Bug report

### Bug description:

Noticed in https://github.com/python/cpython/pull/122917/changes#r2478290584

```python
$ python3 -m sysconfig | grep '= ""[^$]'
	PY_BUILTIN_HASHLIB_HASHES = ""md5,sha1,sha2,sha3,blake2""
```

### CPython versions tested on:

CPython main branch

### Operating systems tested on:

Linux


### Linked PRs
* gh-150209