sanitytest: define long for python version >= 3

Commit c58c7f362a fixed 32-bit python
build but broke build with python3 due to the lack of 'long' in the
newer version of python.  This patch aims to fix it with a simple
string comparison of sys.version and '3'.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

sanitytest.py

@@ -9,6 +9,9 @@ import string
 sys.path.insert(0, sys.argv[1])
 import libvirt
 
+if sys.version > '3':
+    long = int
+
 # Path to the libvirt API XML file
 xml = sys.argv[2]