games/xye: Fix build with Clang 6

src/xsb_level.cpp:787:45: error: constant expression evaluates to -1 which cannot be narrowed to type 'unsigned char' [-Wc++11-narrowing]
    static const unsigned char dx[4] = {0,0,-1,1}, dy[4] = {-1,1,0,0};
                                            ^~

http://beefy12.nyi.freebsd.org/data/head-amd64-default/p475478_s336801/logs/errors/xye-0.12.2_3.log

- While here fix bad absolute symlink

games/xye/Makefile

@@ -3,7 +3,7 @@
 
 PORTNAME=	xye
 PORTVERSION=	0.12.2
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	games
 MASTER_SITES=	SF:game \
 		http://xye.sourceforge.net/levels/ \
@@ -27,10 +27,12 @@ LICENSE=	ZLIB
 
 EXTRACT_DEPENDS=${UNZIP_CMD}:archivers/unzip
 
-USES=		gmake
+USES=		compiler gmake
 USE_SDL=	sdl image ttf
 GNU_CONFIGURE=	yes
 CONFIGURE_ARGS=	--with-docdir=${PREFIX}/share/doc
+CXXFLAGS+=	${CXXFLAGS_${CHOSEN_COMPILER_TYPE}}
+CXXFLAGS_clang=	-Wno-c++11-narrowing
 
 LEVELS=		Xye%20level%20-%204corners Xye%20level%20-%20Against%20the%20force \
 		Xye%20level%20-%20Stop%20that%20cab Xye%20level%20-%20Helping%20Hand \
@@ -89,7 +91,7 @@ post-install:
 	@(cd ${WRKDIR}/skins && ${COPYTREE_SHARE} . ${STAGEDIR}${DATADIR}/res)
 .endif
 
-	${LN} -sf ${DATADIR}/res/detailed_icon.png \
+	${RLN} ${STAGEDIR}${DATADIR}/res/detailed_icon.png \
 		${STAGEDIR}${PREFIX}/share/pixmaps/${PORTNAME}.png
 
 .include <bsd.port.mk>