config: Get rid of the dynamic seen array

* This makes the array constant in the session structure, avoiding
   allocations and frees while parsing the file
 * It also drops passing the seen array to all the functions,
   because it is already part of the passed session
 * The test cases are adjusted to match these changes

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

tests/torture.c

@@ -1163,6 +1163,10 @@ void torture_write_file(const char *filename, const char *data){
     close(fd);
 }
 
+void torture_reset_config(ssh_session session)
+{
+    memset(session->opts.options_seen, 0, sizeof(session->opts.options_seen));
+}
 
 int main(int argc, char **argv) {
     struct argument_s arguments;