configure: allow use of python 3

Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Message-Id: <20180116134217.8725-11-berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

configure

@@ -1604,9 +1604,8 @@ fi
 
 # Note that if the Python conditional here evaluates True we will exit
 # with status 1 which is a shell 'false' value.
-if ! $python -c 'import sys; sys.exit(sys.version_info < (2,6) or sys.version_info >= (3,))'; then
-  error_exit "Cannot use '$python', Python 2.6 or later is required." \
-      "Note that Python 3 or later is not yet supported." \
+if ! $python -c 'import sys; sys.exit(sys.version_info < (2,6))'; then
+  error_exit "Cannot use '$python', Python 2 >= 2.6 or Python 3 is required." \
       "Use --python=/path/to/python to specify a supported Python."
 fi