sysutils/xxd: Make port track vim version, fix WWW

As suggested by adamw, since the port uses the vim distribution,
it can track the vim port PORTVERSION, and use its distfile. [1]

While here:

- Fix WWW, tracking vim one here too [1]
- Adjust COMMENT and pkg-plist a little

Reported by:	adamw [1]
Approved by:	Gianmarco Giovannelli <gmarco@giovannelli.it> (maintainer)

sysutils/xxd/Makefile

@@ -1,14 +1,15 @@
 PORTNAME=	xxd
-DISTVERSIONPREFIX=	v
-DISTVERSION=	9.0.1366
+DISTVERSIONPREFIX=	${VIM_DISTVERSIONPREFIX}
+DISTVERSION=	${VIM_DISTVERSION}
 CATEGORIES=	sysutils
 
 MAINTAINER=	gmarco@giovannelli.it
-COMMENT=	Hexdump and reverse hexdump utility
-WWW=		https://github.com/mew-cx/xxd
+COMMENT=	Hexdump and reverse hexdump utility from vim distribution
+WWW=		${VIM_WWW}
 
 CONFLICTS_INSTALL=	vim-[0-9]* vim-gtk2 vim-gtk3 vim-motif vim-x11
 
+DISTINFO_FILE=	${VIM_PORT}/distinfo
 ALL_TARGET=	${PORTNAME}
 PORTSCOUT=	ignore:1
 EXTRACT_AFTER_ARGS=	--include='*/src/xxd*'
@@ -20,7 +21,14 @@ USE_GITHUB=	yes
 GH_ACCOUNT=	vim
 GH_PROJECT=	vim
 
+.include <bsd.port.pre.mk>
+
+VIM_PORT=		${.CURDIR}/../../editors/vim
+VIM_DISTVERSIONPREFIX!=	${BSDMAKE} -f ${VIM_PORT}/Makefile -V DISTVERSIONPREFIX
+VIM_DISTVERSION!=	${BSDMAKE} -f ${VIM_PORT}/Makefile -V DISTVERSION
+VIM_WWW!=		${BSDMAKE} -f ${VIM_PORT}/Makefile -V WWW
+
 do-install:
 	${INSTALL_PROGRAM} ${WRKSRC}/xxd ${STAGEDIR}${PREFIX}/bin
 
-.include <bsd.port.mk>
+.include <bsd.port.post.mk>

sysutils/xxd/pkg-descr

@@ -1,2 +1,4 @@
-Xxd creates a hex dump of a given file or standard input.
+Standalone xxd utility fromt eh vim editor ditribution.
+
+Xxd creates an hex dump of a given file or standard input.
 It can also convert a hex dump back to its original binary form.