Fix compile error

src/core/ext/transport/chttp2/transport/hpack_parser.c

@@ -1622,13 +1622,13 @@ grpc_error *grpc_chttp2_hpack_parser_parse(grpc_exec_ctx *exec_ctx,
                                            grpc_slice slice) {
 /* max number of bytes to parse at a time... limits call stack depth on
  * compilers without TCO */
-  const size_t max_parse_length = 1024;
+#define MAX_PARSE_LENGTH 1024
   p->current_slice_refcount = slice.refcount;
   uint8_t *start = GRPC_SLICE_START_PTR(slice);
   uint8_t *end = GRPC_SLICE_END_PTR(slice);
   grpc_error *error = GRPC_ERROR_NONE;
   while (start != end && error == GRPC_ERROR_NONE) {
-    uint8_t *target = start + GPR_MIN(max_parse_length, end - start);
+    uint8_t *target = start + GPR_MIN(MAX_PARSE_LENGTH, end - start);
     error = p->state(exec_ctx, p, start, target);
     start = target;
   }