Made the max timeout threshold for SSL longer.

test/test.cc

@@ -8623,7 +8623,7 @@ TEST(MaxTimeoutTest, ContentStream) {
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
 TEST(MaxTimeoutTest, ContentStreamSSL) {
   time_t timeout = 2000;
-  time_t threshold = 500; // SSL_shutdown is slow on some operating systems.
+  time_t threshold = 1200; // SSL_shutdown is slow on some operating systems.
 
   SSLServer svr(SERVER_CERT_FILE, SERVER_PRIVATE_KEY_FILE);