common: add shared synctype_t definition header, borrowed from Quake's modelgen.h

common/synctype.h

@@ -0,0 +1,24 @@
+/*
+synctype.h -- shared synctype_t definition
+Copyright (C) 1996-1997 Id Software, Inc.
+Copyright (C) 2023 Alibek Omarov
+
+This program is free software; you can redistribute it and/or
+modify it under the terms of the GNU General Public License
+as published by the Free Software Foundation; either version 2
+of the License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+*/
+#ifndef SYNCTYPE_H
+#define SYNCTYPE_H
+typedef enum {ST_SYNC=0, ST_RAND } synctype_t;
+#endif