bitbake docs: use dblatex to build the pdf bitbake manual

Fix [BUGID #593]

The current manual build fails for printing formats which use latex as an
intermediate format. This bug has been reported in multiple locations and I
haven't found a solution posted to any of them.

Using --with-dblatex uses dblatex to make the conversion and successfully
generates the pdf. It adds a dependency on dblatex and its dependencies.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
CC: Joshua Lock <josh@linux.intel.com>

bitbake/doc/manual/Makefile

@@ -45,7 +45,7 @@ endif
 	$(call command,xsltproc --stringparam base.dir $@/ $(if $(htmlcssfile),--stringparam html.stylesheet $(htmlcssfile)) $(htmlxsl) $(manual),XSLTPROC $@ $(manual))
 
 $(xmltotypes): $(manual)
-	$(call command,xmlto --extensions -o $(topdir)/$@ $@ $(manual),XMLTO $@ $(manual))
+	$(call command,xmlto --with-dblatex --extensions -o $(topdir)/$@ $@ $(manual),XMLTO $@ $(manual))
 
 clean:
 	rm -rf $(cleanfiles)