Allow hostname checking even when no CA cert was given

src/tls_openssl.h

@@ -4,10 +4,13 @@
 
 #include <openssl/err.h>
 #include <openssl/ssl.h>
+#include <openssl/x509v3.h>
 
 struct mg_tls {
   BIO_METHOD *bm;
   SSL_CTX *ctx;
   SSL *ssl;
+  char *name;       // matching hostname
+  bool check_name;  // set when hostname was set, but no CA certificate given
 };
 #endif