games/palapeli: pacify stage-qa after fca13564

Error: /usr/local/bin/palapeli is linked to /usr/local/lib/libX11.so.6 from x11/libX11 but it is not declared as a dependency
Warning: you need USE_XORG+=x11

Reported by:	portscan

games/palapeli/Makefile

@@ -8,7 +8,7 @@ COMMENT=	${${PORTNAME:tu}_DESC}
 WWW=		https://www.kde.org/applications/games/palapeli/
 
 USES=		cmake compiler:c++11-lang desktop-file-utils kde:5 qt:5 \
-		shared-mime-info tar:xz
+		shared-mime-info tar:xz xorg
 USE_KDE=	archive auth codecs completion config configwidgets coreaddons \
 		crash i18n itemviews jobwidgets kio libkdegames notifications service \
 		solid widgetsaddons windowsystem xmlgui