Unable to compile v3.1.0rc1 with new SSL checks on rh5

Second fix for issue #117

src/check_nrpe.c

@@ -878,7 +878,9 @@ void setup_ssl()
 				break;
 			case TLSv1_2:
 			case TLSv1_2_plus:
+#ifdef SSL_OP_NO_TLSv1_1
 				ssl_opts |= SSL_OP_NO_TLSv1_1;
+#endif
 			case TLSv1_1:
 			case TLSv1_1_plus:
 				ssl_opts |= SSL_OP_NO_TLSv1;