Merge pull request #513 from monaka/pr-not-use-memset-in-structure-initialization3

Use substitution instead of memset in structure initialization.

src/gc.c

@@ -326,6 +326,7 @@ struct RBasic*
 mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
 {
   struct RBasic *p;
+  static const RVALUE RVALUE_zero = { { { 0 } } };
 
 #ifdef MRB_GC_STRESS
   mrb_garbage_collect(mrb);
@@ -345,7 +346,7 @@ mrb_obj_alloc(mrb_state *mrb, enum mrb_vtype ttype, struct RClass *cls)
 
   mrb->live++;
   gc_protect(mrb, p);
-  memset(p, 0, sizeof(RVALUE));
+  *(RVALUE *)p = RVALUE_zero;
   p->tt = ttype;
   p->c = cls;
   paint_partial_white(mrb, p);