include: Fix integer type of dh_pn and dh_pmax

Fixes T188

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

include/libssh/crypto.h

@@ -105,7 +105,7 @@ struct ssh_crypto_struct {
     bignum shared_secret;
     struct dh_ctx *dh_ctx;
 #ifdef WITH_GEX
-    size_t dh_pmin; int dh_pn; int dh_pmax; /* preferred group parameters */
+    size_t dh_pmin; size_t dh_pn; size_t dh_pmax; /* preferred group parameters */
 #endif /* WITH_GEX */
 #ifdef HAVE_ECDH
 #ifdef HAVE_OPENSSL_ECC