g++ -o voteclient voteclient.cpp -I /usr/include/PCSC/ -lcurl -ldl -lsmartcardpp -lcrypto -llsags
You will need mingw32 gcc and libraries, including the windows API files.
sh windows/deps.sh will download the external dependencies to $HOME/mingw32. You'll probably need to tweak some variables in the beginning of the script. sh windows/build.sh downloads and builds LSAGS and this.
If you'd like a binary, there might be one at http://andres.tedx.ee/voteclient.exe and it even might be recent.
GPLv3 but not religious about it.
The exception that allows linking to OpenSSL is in effect. If you are a non-GPL open source project and would like to use the code, contact me about it.