docs: Drop unused rule for internals/%.html.tmp target

We're using the %.html.tmp for all html files now so drop the unused one
and rather make sure the needed directory exists.

This fixes build failures as described in

    https://www.redhat.com/archives/libvir-list/2015-August/msg00603.html

configure.ac

@@ -2777,6 +2777,7 @@ AC_DEFINE_UNQUOTED([isbase64],[libvirt_gl_isbase64],[Hack to avoid symbol clash]
 AC_DEFINE_UNQUOTED([base64_encode],[libvirt_gl_base64_encode],[Hack to avoid symbol clash])
 AC_DEFINE_UNQUOTED([base64_encode_alloc],[libvirt_gl_base64_encode_alloc],[Hack to avoid symbol clash])
 
+AC_CONFIG_COMMANDS([mkdir], [$MKDIR_P docs/internals])
 AC_CONFIG_FILES([run],
                 [chmod +x,-w run])
 AC_CONFIG_FILES([\

docs/Makefile.am

@@ -218,15 +218,6 @@ $(srcdir)/hvsupport.html.in: $(srcdir)/hvsupport.pl $(api_DATA) \
 %.png: %.fig
 	convert -rotate 90 $< $@
 
-internals/%.html.tmp: internals/%.html.in subsite.xsl page.xsl sitemap.html.in
-	@if [ -x $(XSLTPROC) ] ; then \
-	  echo "Generating $@"; \
-	  $(MKDIR_P) internals; \
-	  name=`echo $@ | sed -e 's/.tmp//'`; \
-	  $(XSLTPROC) --stringparam pagename $$name --nonet \
-	    $(top_srcdir)/docs/subsite.xsl $< > $@ \
-	    || { rm $@ && exit 1; }; fi
-
 %.html.tmp: %.html.in site.xsl page.xsl sitemap.html.in $(acl_generated)
 	@if [ -x $(XSLTPROC) ] ; then \
 	  echo "Generating $@"; \