endservent() not present on Windows
gnutls currently fails to build for Windows with these errors:
/local/home/ossman/devel/cenbuild/repo/rpmbuild/BUILD/gnutls-3.4.7/src/socket.c:266: undefined reference to `endservent'
Windows has getservbyname() and such, but not endservent(). I don't think is required functionality, so just adding a dummy replacement for Windows should be fine.