Travis: Fix "Homebrew must be run under Ruby 2.3! (RuntimeError)"

After some change at Travis CI, Mac OS builds are no longer running
with error "Homebrew must be run under Ruby 2.3! (RuntimeError)"

A possible workaround (according to some internet blog) is to set
HOMEBREW_NO_AUTO_UPDATE=1

.travis.yml

@@ -62,7 +62,7 @@ before_script:
       apt-cache search gcc | grep "GNU C compiler";
       apt-cache search clang | grep compiler;
     fi
-  - if [[ "${BUILD_TYPE}" == "OSX_OPENSSL_1_1" ]]; then brew install openssl@1.1 ;fi
+  - if [[ "${BUILD_TYPE}" == "OSX_OPENSSL_1_1" ]]; then HOMEBREW_NO_AUTO_UPDATE=1 brew install openssl@1.1 ;fi
   # Generate the build scripts with CMake
   - mkdir output
   - gcc test/cgi_test.c -o output/cgi_test.cgi

src/civetweb.c

@@ -14369,7 +14369,7 @@ ssl_servername_callback(SSL *ssl, int *ad, void *arg)
 	 * Multiple HTTPS hosts on one IP+port are only possible
 	 * with a certificate containing all alternative names.
 	 */
-	if ((p->servername == NULL) || (*p->servername = 0)) {
+    if ((servername == NULL) || (*servername = 0)) {
 		DEBUG_TRACE("%s", "SSL connection not supporting SNI");
 		return SSL_TLSEXT_ERR_NOACK;
 	}
@@ -14383,7 +14383,7 @@ ssl_servername_callback(SSL *ssl, int *ad, void *arg)
 	 *   SSL_set_SSL_CTX(ssl, matching_ssl_ctx);
 	 * to use this certificate. A different document_root
 	 * may be required as well.
-	*/
+     */
 
 	return SSL_TLSEXT_ERR_OK;
 }