fix buldled static build on Windows/MinGW (#761)
fix buldled static build on Windows/MinGW (#761)

seems like need more libraries in LDFLAGS:

* ws2_32 for socket, connect, htonl, etc
* ole32 for CoInitializeEx
* rpcrt4 for UuidCreate
* crypt32 for CertFreeCertificateContext
libgit2/git2go,libgit2/git2go,clns/git2go,libgit2/git2go,clns/git2go,clns/git2go