quic: fixup duplicate static function name (for cmake unity)

quic: fixup duplicate static function name (for cmake unity)

Visible in daily curl-for-win builds:
https://github.com/curl/curl-for-win/actions/runs/8621925870

```
lib/vquic/curl_ngtcp2.c:1916:12: error: redefinition of 'ossl_new_session_cb'
static int ossl_new_session_cb(SSL *ssl, SSL_SESSION *ssl_sessionid)
           ^
lib/vtls/openssl.c:2978:12: note: previous definition is here
static int ossl_new_session_cb(SSL *ssl, SSL_SESSION *ssl_sessionid)
           ^
```
https://github.com/curl/curl-for-win/actions/runs/8621925870/job/23631885439#step:3:6965

Follow-up to 3210101088dfa3d6a125d213226b092f2f866722 #13172
Closes #13332