build: fix building rare combinations

- http/2 + !headers
- gnutls + !verbose
- ssls-export + !verbose

Closes #20712

lib/headers.h

@@ -55,7 +55,8 @@ CURLcode Curl_headers_cleanup(struct Curl_easy *data);
 
 #else
 #define Curl_headers_init(x)          CURLE_OK
-#define Curl_headers_push(x, y, z, a) CURLE_OK
+#define Curl_headers_push(x, y, z, a) \
+  ((void)(x), (void)(y), (void)(z), (void)(a), CURLE_OK)
 #define Curl_headers_cleanup(x)       Curl_nop_stmt
 #endif
 

lib/vquic/curl_ngtcp2.c

@@ -2341,6 +2341,7 @@ static int quic_ossl_new_session_cb(SSL *ssl, SSL_SESSION *ssl_sessionid)
 
 #ifdef USE_GNUTLS
 
+#ifdef CURLVERBOSE
 static const char *gtls_hs_msg_name(int mtype)
 {
   switch(mtype) {
@@ -2367,6 +2368,7 @@ static const char *gtls_hs_msg_name(int mtype)
   }
   return "Unknown";
 }
+#endif
 
 static int quic_gtls_handshake_cb(gnutls_session_t session, unsigned int htype,
                                   unsigned when, unsigned int incoming,

lib/vtls/vtls_scache.c

@@ -1148,9 +1148,12 @@ CURLcode Curl_ssl_session_export(struct Curl_easy *data,
   struct Curl_ssl_scache_peer *peer;
   struct dynbuf sbuf, hbuf;
   struct Curl_llist_node *n;
-  size_t i, npeers = 0, ntickets = 0;
+  size_t i;
   curl_off_t now = time(NULL);
   CURLcode r = CURLE_OK;
+#ifdef CURLVERBOSE
+  size_t npeers = 0, ntickets = 0;
+#endif
 
   if(!export_fn)
     return CURLE_BAD_FUNCTION_ARGUMENT;
@@ -1173,7 +1176,7 @@ CURLcode Curl_ssl_session_export(struct Curl_easy *data,
     cf_scache_peer_remove_expired(peer, now);
     n = Curl_llist_head(&peer->sessions);
     if(n)
-      ++npeers;
+      VERBOSE(++npeers);
     while(n) {
       struct Curl_ssl_session *s = Curl_node_elem(n);
       if(!peer->hmac_set) {
@@ -1201,7 +1204,7 @@ CURLcode Curl_ssl_session_export(struct Curl_easy *data,
                     s->alpn, s->earlydata_max);
       if(r)
         goto out;
-      ++ntickets;
+      VERBOSE(++ntickets);
       n = Curl_node_next(n);
     }
   }