Use GnuTLS instead of OpenSSL

1.1 Download source
1.2 ./configure && make && make install

2 Build libhogweed and libnettle

2.1 Download source
2.2 ./configure && make && make install

3 Build civetweb

make build WITH_GNUTLS=1

4 Run civetweb

export LD_LIBRARY_PATH=/usr/local/lib/:$LD_LIBRARY_PATH
./civetweb -listening_ports 8443s -ssl_certificate resources/cert/server.pem -document_root ./test/htmldir/