hghave: use print function

For Python 3 compatibility.

tests/hghave

@@ -3,6 +3,9 b''
 if all features are there, non-zero otherwise. If a feature name is
 prefixed with "no-", the absence of feature is tested.
 """
+
+from __future__ import print_function
+
 import optparse
 import os, sys
 import hghave
@@ -12,7 +15,7 b' checks = hghave.checks'
 def list_features():
     for name, feature in sorted(checks.iteritems()):
         desc = feature[1]
-        print name + ':', desc
+        print(name + ':', desc)
 
 def test_features():
     failed = 0
@@ -21,7 +24,7 b' def test_features():'
         try:
             check()
         except Exception as e:
-            print "feature %s failed:  %s" % (name, e)
+            print("feature %s failed:  %s" % (name, e))
             failed += 1
     return failed