Patch from Tremulous / description from Zack Middleton: (#5041)

Clear game logfile handle after closing file.

Game does not clear logFile handle when closing file. Might be an issue if
G_LogPrintf is called after this.

Patch from tremulous http://svn.icculus.org/tremulous?view=rev&revision=2041

code/game/g_main.c

@@ -524,6 +524,7 @@ void G_ShutdownGame( int restart ) {
 		G_LogPrintf("ShutdownGame:\n" );
 		G_LogPrintf("------------------------------------------------------------\n" );
 		trap_FS_FCloseFile( level.logFile );
+		level.logFile = 0;
 	}
 
 	// write all the client session data so we can get it back