enable v8plus_call to be used in any thread

*** 414,424 ****
  
          return (exception);
  }
  
  extern "C" nvlist_t *
! v8plus_call(v8plus_jsfunc_t f, const nvlist_t *lp)
  {
          std::unordered_map<uint64_t, cb_hdl_t>::iterator it;
          const int max_argc = nvlist_length(lp);
          int argc, err;
          v8::Handle<v8::Value> argv[max_argc];
--- 414,424 ----
  
          return (exception);
  }
  
  extern "C" nvlist_t *
! v8plus_call_direct(v8plus_jsfunc_t f, const nvlist_t *lp)
  {
          std::unordered_map<uint64_t, cb_hdl_t>::iterator it;
          const int max_argc = nvlist_length(lp);
          int argc, err;
          v8::Handle<v8::Value> argv[max_argc];
*** 524,534 ****
          }
          ++it->second.ch_refs;
  }
  
  extern "C" void
! v8plus_jsfunc_rele(v8plus_jsfunc_t f)
  {
          v8::Local<v8::Function> lfh;
          std::unordered_map<uint64_t, cb_hdl_t>::iterator it;
  
          if ((it = cbhash.find(f)) == cbhash.end())
--- 524,534 ----
          }
          ++it->second.ch_refs;
  }
  
  extern "C" void
! v8plus_jsfunc_rele_direct(v8plus_jsfunc_t f)
  {
          v8::Local<v8::Function> lfh;
          std::unordered_map<uint64_t, cb_hdl_t>::iterator it;
  
          if ((it = cbhash.find(f)) == cbhash.end())
*** 638,647 ****
          v8plus::ObjectWrap *op = v8plus::ObjectWrap::objlookup(cop);
          op->public_Ref();
  }
  
  extern "C" void
! v8plus_obj_rele(const void *cop)
  {
          v8plus::ObjectWrap *op = v8plus::ObjectWrap::objlookup(cop);
          op->public_Unref();
  }
--- 638,647 ----
          v8plus::ObjectWrap *op = v8plus::ObjectWrap::objlookup(cop);
          op->public_Ref();
  }
  
  extern "C" void
! v8plus_obj_rele_direct(const void *cop)
  {
          v8plus::ObjectWrap *op = v8plus::ObjectWrap::objlookup(cop);
          op->public_Unref();
  }