libvncserver: improved to disable gcrypt support if it is not available and to provide some hint where to find it if available

x11/libvncserver/libvncserver.conf

@@ -20,3 +20,9 @@ if atstage cross; then
 	# assume we have gettimeofday()
 	var_append configcache ' ' "ac_cv_func_gettimeofday=yes"
 fi
+
+if ! pkginstalled -f libgcrypt; then
+	var_append extraconfopt ' ' "--without-gcrypt"
+else
+	var_append extraconfopt ' ' "--with-libgcrypt-prefix=$( pkgprefix -r libgcrypt )"
+fi