zero init mrc_parser_state

Author: hasumikin

src/ccontext.c

@@ -8,7 +8,7 @@ mrc_ccontext_new(mrb_state *mrb)
   mrc_ccontext temp_c = {0};
   temp_c.mrb = mrb;
   mrc_ccontext *c = (mrc_ccontext *)mrc_calloc((&temp_c), 1, sizeof(mrc_ccontext));
-  c->p = (mrc_parser_state *)mrc_malloc((&temp_c), sizeof(mrc_parser_state));
+  c->p = (mrc_parser_state *)mrc_calloc((&temp_c), 1, sizeof(mrc_parser_state));
   c->options = NULL;
   c->mrb = temp_c.mrb;
   return c;