[FIX] Fix issue with TypedPackedFunc template instatition (#1649)

include/tvm/runtime/packed_func.h

@@ -180,9 +180,7 @@ class TypedPackedFunc<R(Args...)> {
    *
    * \param packed The packed function
    */
-  explicit TypedPackedFunc(PackedFunc packed)
-      : packed_(packed) {
-  }
+  inline explicit TypedPackedFunc(PackedFunc packed);
   /*!
    * \brief construct from a lambda function with the same signature.
    *
@@ -925,6 +923,8 @@ inline PackedFunc::FType PackedFunc::body() const {
   return body_;
 }
 
+
+
 // internal namespace
 namespace detail {
 
@@ -1132,6 +1132,10 @@ struct typed_packed_call_dispatcher<void> {
 }  // namespace detail
 
 template<typename R, typename ...Args>
+TypedPackedFunc<R(Args...)>::TypedPackedFunc(PackedFunc packed)
+  : packed_(packed) {}
+
+template<typename R, typename ...Args>
 template<typename FType>
 inline void TypedPackedFunc<R(Args...)>::AssignTypedLambda(FType flambda) {
   packed_ = PackedFunc([flambda](const TVMArgs& args, TVMRetValue* rv) {