gnu90 compatibility (#1512)

Author: mahajanadhitya

src/confluent_kafka/src/Consumer.c

@@ -970,8 +970,8 @@ static PyObject *Consumer_poll (Handle *self, PyObject *args,
 
         msgobj = Message_new0(self, rkm);
 #ifdef RD_KAFKA_V_HEADERS
-        // Have to detach headers outside Message_new0 because it declares the
-        // rk message as a const
+        /** Have to detach headers outside Message_new0 because it declares the
+          * rk message as a const */
         rd_kafka_message_detach_headers(rkm, &((Message *)msgobj)->c_headers);
 #endif
         rd_kafka_message_destroy(rkm);
@@ -1062,8 +1062,8 @@ static PyObject *Consumer_consume (Handle *self, PyObject *args,
         for (i = 0; i < n; i++) {
                 PyObject *msgobj = Message_new0(self, rkmessages[i]);
 #ifdef RD_KAFKA_V_HEADERS
-                // Have to detach headers outside Message_new0 because it declares the
-                // rk message as a const
+                /** Have to detach headers outside Message_new0 because it declares the
+                  * rk message as a const */
                 rd_kafka_message_detach_headers(rkmessages[i], &((Message *)msgobj)->c_headers);
 #endif
                 PyList_SET_ITEM(msglist, i, msgobj);

src/confluent_kafka/src/confluent_kafka.c

@@ -1318,7 +1318,7 @@ PyObject *c_headers_to_py (rd_kafka_headers_t *headers) {
 
     while (!rd_kafka_header_get_all(headers, idx++,
                                      &header_key, &header_value, &header_value_size)) {
-            // Create one (key, value) tuple for each header
+            /* Create one (key, value) tuple for each header */
             PyObject *header_tuple = PyTuple_New(2);
             PyTuple_SetItem(header_tuple, 0,
                 cfl_PyUnistr(_FromString(header_key))
@@ -1694,7 +1694,8 @@ static void oauth_cb (rd_kafka_t *rk, const char *oauthbearer_config,
                                                   sizeof(err_msg));
         Py_DECREF(result);
         if (rd_extensions) {
-                for(int i = 0; i < rd_extensions_size; i++) {
+                int i;
+                for(i = 0; i < rd_extensions_size; i++) {
                         free(rd_extensions[i]);
                 }
                 free(rd_extensions);
@@ -2739,7 +2740,7 @@ static char *KafkaError_add_errs (PyObject *dict, const char *origdoc) {
 
 	_PRINT("\n");
 
-	return doc; // FIXME: leak
+	return doc; /* FIXME: leak */
 }