python: Implement Pointer ("virDomainPtr", _) (RHBZ#1075164).

This allows the Python binding of guestfs_add_libvirt_dom to work.

There is a regression test to ensure this keeps working.

Note this requires a patched libvirt-python, supporting the
c_pointer() method.

python/run-python-tests

@@ -18,6 +18,9 @@
 
 errors=0
 
+guestsdir="$(cd ../tests/guests && pwd)"
+export guestsdir
+
 for f in $srcdir/t/*.py; do
   $PYTHON $f
   r=$?

python/t/910-libvirt.py

@@ -0,0 +1,48 @@
+# libguestfs Python bindings
+# Copyright (C) 2014 Red Hat Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+# The Python bindings for add_libvirt_dom require the libvirt-python
+# library to support a new method (.c_pointer()).  Ensure this keeps
+# working by testing it.  See:
+# https://bugzilla.redhat.com/show_bug.cgi?id=1075164
+
+import os
+import guestfs
+
+guestsdir = os.environ['guestsdir']
+
+try:
+    import libvirt
+except:
+    print "could not import python-libvirt"
+    exit (77)
+
+conn = libvirt.open ("test:///%s/guests.xml" % guestsdir)
+
+# Check we're using the version of libvirt-python that has c_pointer() methods.
+if not "c_pointer" in dir (conn):
+    print "skipping test: libvirt-python doesn't support c_pointer()"
+    exit (77)
+
+dom = conn.lookupByName ("blank-disk")
+
+g = guestfs.GuestFS ()
+
+r = g.add_libvirt_dom (dom, readonly=1)
+
+if r != 1:
+    raise "unexpected return value from add_libvirt_dom (%d)" % r