gnutls: fix clang-tidy warning with !verbose

with
`-DCURL_DISABLE_VERBOSE_STRINGS=ON -DCURL_USE_GNUTLS=ON -DCURL_CLANG_TIDY=ON`.

```
lib/vtls/gtls.c:268:7: error: Value stored to 'strerr' is never read [clang-analyzer-deadcode.DeadStores,-warnings-as-errors]
  268 |       strerr = gnutls_strerror(rc);
      |       ^        ~~~~~~~~~~~~~~~~~~~
```

Closes #21060

diff --git a/lib/vtls/gtls.c b/lib/vtls/gtls.c
index 4ac1913240dce89f206a7e218ff2086666cec2db..b52cc911ffba27f983ffba4e557d17da523c2132 100644 (file)
--- a/lib/vtls/gtls.c
+++ b/lib/vtls/gtls.c
@@ -257,6 +257,7 @@ static CURLcode cf_gtls_handshake(struct Curl_cfilter *cf,
     return CURLE_AGAIN;
   }
   else if((rc < 0) && !gnutls_error_is_fatal(rc)) {
+#ifdef CURLVERBOSE
     const char *strerr = NULL;
 
     if(rc == GNUTLS_E_WARNING_ALERT_RECEIVED) {
@@ -268,6 +269,7 @@ static CURLcode cf_gtls_handshake(struct Curl_cfilter *cf,
       strerr = gnutls_strerror(rc);
 
     infof(data, "gnutls_handshake() warning: %s", strerr);
+#endif
     return CURLE_AGAIN;
   }
   else if((rc < 0) && backend->gtls.io_result) {