xm: xen-api: Install create.dtd in SHAREDIR

* Install create.dtd in SHAREDIR
* Use SHAREDIR/create.dtd
* import os.path.join into xenapi_create.py,
  it already seems to be used many times

Resolves the following error when using XenAPI:

$ xm create hvm.conf
Couldn't open resource '/usr/share/xen/create.dtd' at
/usr/share/xen/create.dtd:1:0

Signed-off-by: Simon Horman <horms@verge.net.au>

tools/python/Makefile

@@ -22,6 +22,7 @@ genpath:
 	echo "BINDIR=\"$(BINDIR)\"" >> ${xenpath}
 	echo "LIBEXEC=\"$(LIBEXEC)\"" >> ${xenpath}
 	echo "LIBDIR=\"$(LIBDIR)\"" >> ${xenpath}
+	echo "SHAREDIR=\"$(SHAREDIR)\"" >> ${xenpath}
 	echo "PRIVATE_BINDIR=\"$(PRIVATE_BINDIR)\"" >> ${xenpath}
 	echo "XEN_CONFIG_DIR=\"$(XEN_CONFIG_DIR)\"" >> ${xenpath}
 	echo "XEN_SCRIPT_DIR=\"$(XEN_SCRIPT_DIR)\"" >> ${xenpath}
@@ -70,8 +71,8 @@ install: install-messages install-dtd
 		$(PYTHON_PREFIX_ARG) --root="$(DESTDIR)" --force
 
 install-dtd: all
-	$(INSTALL_DIR) $(DESTDIR)$(DOCDIR)
-	$(INSTALL_DATA) xen/xm/create.dtd $(DESTDIR)$(DOCDIR)
+	$(INSTALL_DIR) $(DESTDIR)$(SHAREDIR)
+	$(INSTALL_DATA) xen/xm/create.dtd $(DESTDIR)$(SHAREDIR)
 
 install-messages: all
 	set -e; if which $(MSGFMT) >/dev/null ; then \