docs: drop XHTML 1.0 validation of website

The HTML pages are currently validated against an XHTML 1.0 DTD.
This makes it impossible to take advantage of features that are
introduced in HTML 5, because they'll fail validation.

There is intentionally no DTD defined for HTML 5, so there's no
alternative to XHTML 1.0 DTD that we could switch to. The only
options are to stick with XHTML 1.0 forever, or drop the DTD
validation, and we pick the latter.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

.travis.yml

@@ -38,7 +38,6 @@ addons:
       - libapparmor-dev
       - dnsmasq-base
       - librbd-dev
-      - w3c-dtd-xhtml
 
 notifications:
   irc:

docs/Makefile.am

@@ -268,14 +268,10 @@ MAINTAINERCLEANFILES += \
 	    || { rm $@ && exit 1; }; fi
 
 %.html: %.html.tmp
-	@if test -x $(XMLLINT) && test -x $(XMLCATALOG) ; then \
-	  if $(XMLCATALOG) '$(XML_CATALOG_FILE)' \
-	    "-//W3C//DTD XHTML 1.0 Strict//EN" > /dev/null ; then \
+	@if test -x $(XMLLINT) ; then \
 	  echo "Validating $@" ; \
-	  SGML_CATALOG_FILES='$(XML_CATALOG_FILE)' \
-	  $(XMLLINT) --catalogs --nonet --format --valid $< > $(srcdir)/$@ \
-	  || { rm $(srcdir)/$@ && exit 1; }; \
-	  else echo "missing XHTML1 DTD"; cat $< > $(srcdir)/$@ ; fi ; fi
+	  $(XMLLINT) --nonet --format $< > $(srcdir)/$@ \
+	  || { rm $(srcdir)/$@ && exit 1; }; fi
 
 %.php.tmp: %.php.in site.xsl page.xsl
 	if [ -x $(XSLTPROC) ] ; then \
@@ -300,12 +296,8 @@ html/index.html: libvirt-api.xml newapi.xsl page.xsl $(APIBUILD_STAMP)
 	  --stringparam builddir '$(abs_top_builddir)' \
 	  --stringparam timestamp $(timestamp) \
 	  $(srcdir)/newapi.xsl $(srcdir)/libvirt-api.xml ; fi && \
-	if test -x $(XMLLINT) && test -x $(XMLCATALOG) ; then \
-	  if $(XMLCATALOG) '$(XML_CATALOG_FILE)' "-//W3C//DTD XHTML 1.0 Strict//EN" \
-	    > /dev/null ; then \
-	  SGML_CATALOG_FILES='$(XML_CATALOG_FILE)' \
-	  $(XMLLINT) --catalogs --nonet --valid --noout $(srcdir)/html/*.html ; \
-	  else echo "missing XHTML1 DTD"; cat $< > $(srcdir)/$@ ; fi ; fi
+	if test -x $(XMLLINT) ; then \
+	  $(XMLLINT) --nonet --noout $(srcdir)/html/*.html ; fi
 
 $(addprefix $(srcdir)/,$(devhelphtml)): $(srcdir)/libvirt-api.xml $(devhelpxsl)
 	$(AM_V_GEN)if [ -x $(XSLTPROC) ] ; then \

libvirt.spec.in

@@ -301,7 +301,6 @@ BuildRequires: systemd-units
 BuildRequires: xen-devel
 %endif
 BuildRequires: libxml2-devel
-BuildRequires: xhtml1-dtds
 BuildRequires: libxslt
 BuildRequires: readline-devel
 BuildRequires: ncurses-devel

m4/virt-external-programs.m4

@@ -24,7 +24,6 @@ AC_DEFUN([LIBVIRT_CHECK_EXTERNAL_PROGRAMS], [
 
   dnl Miscellaneous external programs.
   AC_PATH_PROG([XMLLINT], [xmllint], [/usr/bin/xmllint])
-  AC_PATH_PROG([XMLCATALOG], [xmlcatalog], [/usr/bin/xmlcatalog])
   AC_PATH_PROG([XSLTPROC], [xsltproc], [/usr/bin/xsltproc])
   AC_PATH_PROG([AUGPARSE], [augparse], [/usr/bin/augparse])
   AC_PROG_MKDIR_P