XSLTPROC and TIDY are not specific to either DocBook or HTML formats,

so move the associated variables to doc.project.mk instead of
duplicating the definitions for each doc type.

share/mk/doc.docbook.mk

@@ -171,7 +171,6 @@ CATALOG_PORTS_SGML=	${PREFIX}/share/sgml/catalog.ports
 DSSSLCATALOG=	${PREFIX}/share/sgml/docbook/dsssl/modular/catalog
 COLLATEINDEX=	${PREFIX}/share/sgml/docbook/dsssl/modular/bin/collateindex.pl
 
-XSLTPROC?=	${PREFIX}/bin/xsltproc
 XSLTPROCFLAGS?=	--nonet
 XSLHTML?=	${DOC_PREFIX}/share/xsl/freebsd-html.xsl
 XSLHTMLCHUNK?=	${DOC_PREFIX}/share/xsl/freebsd-html-chunk.xsl
@@ -264,7 +263,6 @@ PDFTEX_CMD?=	${PREFIX}/bin/pdftex
 JADETEX_CMD?=	${TEX_CMD} "&jadetex"
 PDFJADETEX_CMD?=${PDFTEX_CMD} "&pdfjadetex"
 GROFF?=		groff
-TIDY?=		${PREFIX}/bin/tidy
 TIDYOPTS?=	-wrap 90 -m -raw -preserve -f /dev/null -asxml ${TIDYFLAGS}
 HTML2TXT?=	${PREFIX}/bin/links
 HTML2TXTOPTS?=	-dump ${HTML2TXTFLAGS}

share/mk/doc.html.mk

@@ -67,7 +67,6 @@ PKG_CREATE?=	/usr/sbin/pkg_create
 TAR?=		/usr/bin/tar
 XARGS?=		/usr/bin/xargs
 
-TIDY?=		${PREFIX}/bin/tidy
 TIDYOPTS?=	-i -m -raw -preserve -f /dev/null -asxml ${TIDYFLAGS}
 HTML2PDB?=	${PREFIX}/bin/iSiloBSD
 HTML2PDBOPTS?=	-y -d0 -Idef ${HTML2PDBFLAGS}

share/mk/doc.project.mk

@@ -91,6 +91,8 @@ PERL?=		perl
 .endif
 REALPATH?=	/bin/realpath
 SETENV?=	/usr/bin/env
+XSLTPROC?=	${PREFIX}/bin/xsltproc
+TIDY?=		${PREFIX}/bin/tidy
 
 # Image processing (contains code used by the doc.<format>.mk files, so must
 # be listed first).