crypto: do not include gmp.h

It is unused.

Author: illwieckz

src/engine/qcommon/crypto.h

@@ -27,11 +27,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "q_shared.h"
 #include "qcommon.h"
 
-#pragma warning(push)
-#pragma warning(disable : 4146) // "unary minus operator applied to unsigned type, result still unsigned"
-#include <gmp.h>
-#pragma warning(pop)
-
 #include <nettle/bignum.h>
 #include <nettle/rsa.h>
 #include <nettle/buffer.h>