[Runtime] Export GraphRuntime in tvm_runtime.dll (#5002)

Co-authored-by: Jon Soifer <jonso@microsoft.com>

src/runtime/graph/graph_runtime.h

@@ -65,7 +65,7 @@ struct TVMOpParam {
  *  This runtime can be acccesibly in various language via
  *  TVM runtime PackedFunc API.
  */
-class GraphRuntime : public ModuleNode {
+class TVM_DLL GraphRuntime : public ModuleNode {
   struct OpArgs {
     std::vector<DLTensor> args;
     std::vector<TVMValue> arg_values;