The "SHA256"/"SHA384" cipher aliases fail to be killed/removed simultaneously in non-strict mode

### Problem:

When using `SSL_CTX_set_cipher_list`, AWS-LC fails if both `SHA256` and `SHA384` aliases are either killed or removed.

Considering the following code:

```
#include

#include

static const char *list[] = {
"HIGH:!SHA256:!SHA384", "HIGH:-SHA256:!SHA384", "HIGH:+SHA256:!SHA384",
"HIGH:!SHA256:-SHA384", "HIGH:-SHA256:-SHA384", "HIGH:+SHA256:-SHA384",
"HIGH:!SHA256:+SHA384", "HIGH:-SHA256:+SHA384", "HIGH:+SHA256:+SHA384",
"HIGH:!SHA1:!SHA384", "HIGH:-SHA1:!SHA384", "HIGH:+SHA1:!SHA384",
"HIGH:!SHA1:-SHA384", "HIGH:-SHA1:-SHA384", "HIGH:+SHA1:-SHA384",
"HIGH:!SHA1:+SHA384", "HIGH:-SHA1:+SHA384", "HIGH:+SHA1:+SHA384",
"HIGH:!OwO:!SHA384", "HIGH:-OwO:!SHA384", "HIGH:+OwO:!SHA384",
"HIGH:!OwO:-SHA384", "HIGH:-OwO:-SHA384", "HIGH:+OwO:-SHA384",
"HIGH:!OwO:+SHA384", "HIGH:-OwO:+SHA384", "HIGH:+OwO:+SHA384",
};

int
main() {
__auto_type ctx = SSL_CTX_new(TLS_client_method());

for (__auto_type i = 0; i < 27; i++) {
if (SSL_CTX_set_cipher_list(ctx, list[i]) != 1) {
fprintf(stderr, "%s\n", list[i]);
}
}
}
```

With AWS-LC, I get the following output whereas it should've been empty:

```
HIGH:!SHA256:!SHA384
HIGH:-SHA256:!SHA384
HIGH:!SHA256:-SHA384
HIGH:-SHA256:-SHA384
```

### Requirements / Acceptance Criteria:

* **RFC links:** n/a
* **Related Issues:** n/a
* **Will the Usage Guide or other documentation need to be updated?** no
* **Testing:** Maybe a couple more cases in the TLS 1.2 ciphers unit tests
* **Will this change trigger AWS LibCrypto Formal Verification changes?** no
* **Should this change be fuzz tested?** no

Start at SSL_CTX_set_cipher_list and the TLS 1.2 ciphers unit tests mentioned in the issue. Reproduce the 27 cipher-list cases, then trace how the SHA256 and SHA384 aliases are processed in non-strict mode. Done means the four currently failing combinations are accepted and the unit tests cover the regression.

Written by the indexing model from the issue text.