Bug: Wrong limit for local variables in 16-bit systems

USHRT_MAX does not fit in an 'int' in 16-bit systems.

lapi.c

@@ -1343,7 +1343,7 @@ void lua_warning (lua_State *L, const char *msg, int tocont) {
 LUA_API void *lua_newuserdatauv (lua_State *L, size_t size, int nuvalue) {
   Udata *u;
   lua_lock(L);
-  api_check(L, 0 <= nuvalue && nuvalue < USHRT_MAX, "invalid value");
+  api_check(L, 0 <= nuvalue && nuvalue < SHRT_MAX, "invalid value");
   u = luaS_newudata(L, size, nuvalue);
   setuvalue(L, s2v(L->top.p), u);
   api_incr_top(L);

lparser.c

@@ -198,7 +198,7 @@ static int new_localvar (LexState *ls, TString *name) {
   checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
                  MAXVARS, "local variables");
   luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
-                  dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
+                  dyd->actvar.size, Vardesc, SHRT_MAX, "local variables");
   var = &dyd->actvar.arr[dyd->actvar.n++];
   var->vd.kind = VDKREG;  /* default */
   var->vd.name = name;