Case VVARGIND added to luaK_storevar

In a global initialization, the variable does not pass through
'check_readonly', and therefore a VVARGIND is not normalized to a
VINDEXED.

lcode.c

@@ -1109,6 +1109,10 @@ void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
       codeABRK(fs, OP_SETFIELD, var->u.ind.t, var->u.ind.idx, ex);
       break;
     }
+    case VVARGIND: {
+      fs->f->flag |= PF_VATAB;  /* function will need a vararg table */
+      /* now, assignment is to a regular table */
+    }  /* FALLTHROUGH */
     case VINDEXED: {
       codeABRK(fs, OP_SETTABLE, var->u.ind.t, var->u.ind.idx, ex);
       break;

testes/vararg.lua

@@ -184,6 +184,18 @@ do  -- _ENV as vararg parameter
       a = 10
     end ]]
   assert(string.find(msg, "const variable 'a'"))
+
+  local function aux (... | _ENV)
+    global a; a = 10
+    return a
+  end
+  assert(aux() == 10)
+
+  local function aux (... | _ENV)
+    global a = 10
+    return a
+  end
+  assert(aux() == 10)
 end