Use correct ifdefs for checking TLS 1.3

TLS 1.3 is not ready yet in LibreSSL. Also there is a theoretical
possibility of OpenSSL >=1.1.1 built without TLS 1.3 support

src/httperf.c

@@ -687,7 +687,7 @@ main(int argc, char **argv)
                                 param.ssl_protocol = 5;
 			    else if (strcasecmp (optarg, "TLSv1.2") == 0 || strcasecmp (optarg, "TLSv1_2") == 0)
                                 param.ssl_protocol = 6;
-#if (OPENSSL_VERSION_NUMBER >= 0x10101000L)
+#ifdef TLS1_3_VERSION
                             else if (strcasecmp (optarg, "TLSv1.3") == 0 || strcasecmp (optarg, "TLSv1_3") == 0)
                                 param.ssl_protocol = 7;
 #endif
@@ -1104,7 +1104,7 @@ main(int argc, char **argv)
 		    SSL_CTX_set_options(ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_TLSv1 | SSL_OP_NO_TLSv1_1); break;
 #endif
 
-#if (OPENSSL_VERSION_NUMBER >= 0x10101000L)
+#ifdef TLS1_3_VERSION
                     /* 7/TLSv1.3 */
 		    case 7:
                     ssl_ctx = SSL_CTX_new (TLS_client_method ());
@@ -1329,7 +1329,7 @@ main(int argc, char **argv)
             case 4: printf (" --ssl-protocol=TLSv1.0"); break;
 	    case 5: printf (" --ssl-protocol=TLSv1.1"); break;
 	    case 6: printf (" --ssl-protocol=TLSv1.2"); break;
-#if (OPENSSL_VERSION_NUMBER >= 0x10101000L)
+#ifdef TLS1_3_VERSION
             case 7: printf (" --ssl-protocol=TLSv1.3"); break;
 #endif
         }