Thanks for sharing @alphabeta...
To use @bitcube's external "secp256k1.dll". Open it's property and change Target Extension from ".lib" to ".dll", and Configuration type from "static" to "dynamic".
Which solution I need to edit for this? secp256k1 or steemd?
right click "secp256k1" scroll down to property and make the changes.
Edit:
Make sure you hit apply after the change.