Pass more args to custom TLS init

src/tls.h

@@ -11,7 +11,7 @@ struct mg_tls_opts {
   const char *certkey;    // Certificate key
   const char *ciphers;    // Cipher list
   struct mg_str srvname;  // If not empty, enables server name verification
-  int (*ifn)(struct mg_tls_opts *);  // Custom init func. Return 0 on success
+  int (*custom_init)(struct mg_connection *, struct mg_tls_opts *, void *tls);
 };
 
 void mg_tls_init(struct mg_connection *, struct mg_tls_opts *);

src/tls_mbed.c

@@ -58,7 +58,8 @@ void mg_tls_init(struct mg_connection *c, struct mg_tls_opts *opts) {
   if (tls == NULL) {
     mg_error(c, "TLS OOM");
     goto fail;
-  } else if (opts->ifn != NULL && opts->ifn(opts) != 0) {
+  } else if (opts->custom_init != NULL &&
+             opts->custom_init(c, opts, tls) != 0) {
     mg_error(c, "TLS custom init failed");
     goto fail;
   }

src/tls_openssl.c

@@ -28,7 +28,8 @@ void mg_tls_init(struct mg_connection *c, struct mg_tls_opts *opts) {
   if (tls == NULL) {
     mg_error(c, "TLS OOM");
     goto fail;
-  } else if (opts->ifn != NULL && opts->ifn(opts) != 0) {
+  } else if (opts->custom_init != NULL &&
+             opts->custom_init(c, opts, tls) != 0) {
     mg_error(c, "TLS custom init failed");
     goto fail;
   }