Fix lightmap corruption that happens after a while.

git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@6234 fc73d0e0-1445-4013-8a0c-d673dee63da5

engine/gl/gl_model.c

@@ -1115,6 +1115,7 @@ static void Mod_LoadModelWorker (void *ctx, void *data, size_t a, size_t b)
 // load the file
 //
 	mod->maxlod = 0;
+	mod->lightmaps.first = 0;
 	// set necessary engine flags for loading purposes
 	if (!strcmp(mod->publicname, "progs/player.mdl"))
 		mod->engineflags |= MDLF_PLAYER | MDLF_DOCRC;