Support compilinig 国密 contract with library

[leayingly]

Currently compilation will throw "libraries linking is not supported under SM_CRYPTO mode".

The idea of solc linker is to replace __$xxxxx$__ placeholder(hash of library name) in compiled contract with deployed address of that library.

For ECDSA it's using solidity Keccak256 to hash library name. For GM is it sm3?

[vita-dounai]

頑張ってください‼