Clear startdemo list on game change

This fixes inconsistent behavior when starting a game with -ad
vs starting with id1 and using 'game ad' in the console
(since id1 has startdemos in its quake.rc file, while ad doesn't).

Quake/common.c

@@ -2202,6 +2202,7 @@ static void COM_Game_f (void)
 			R_NewGame ();
 		}
 		ExtraMaps_NewGame ();
+		Host_Resetdemos ();
 		DemoList_Rebuild ();
 
 		Con_Printf("\"game\" changed to \"%s\"\n", COM_SkipPath(com_gamedir));

Quake/host_cmd.c

@@ -2271,6 +2271,19 @@ static void Host_Stopdemo_f (void)
 	CL_Disconnect ();
 }
 
+/*
+==================
+Host_Resetdemos
+
+Clear looping demo list (called on game change)
+==================
+*/
+void Host_Resetdemos (void)
+{
+	memset (cls.demos, 0, sizeof (cls.demos));
+	cls.demonum = 0;
+}
+
 //=============================================================================
 
 /*

Quake/quakedef.h

@@ -315,6 +315,7 @@ void Host_Quit_f (void);
 void Host_ClientCommands (const char *fmt, ...) FUNC_PRINTF(1,2);
 void Host_ShutdownServer (qboolean crash);
 void Host_WriteConfiguration (void);
+void Host_Resetdemos (void);
 
 void ExtraMaps_Init (void);
 void Modlist_Init (void);