hw/xwin: Add missing FORCEEXIT token to XWin configuration file lexer

Somehow this was left out of commmit f3fad371cc

Signed-off-by: Colin Harrison <colin.harrison@virgin.net>
Reviewed-by: Jon TURNEY <jon.turney@dronecode.org.uk>

hw/xwin/winprefslex.l

@@ -90,6 +90,7 @@ ALWAYSONTOP             { return ALWAYSONTOP; }
 DEBUG                   { return DEBUGOUTPUT; }
 RELOAD                  { return RELOAD; }
 TRAYICON                { return TRAYICON; }
+FORCEEXIT		{ return FORCEEXIT; }
 SILENTEXIT		{ return SILENTEXIT; }
 "{"                     { return LB; }
 "}"                     { return RB; }