revlog: use int instead of long

revlog: use int instead of long

By my reading of PEP 237[0], this is completely safe and has been
since Python 2.2.

0: https://www.python.org/dev/peps/pep-0237/

--- a/mercurial/revlog.py	Sun Mar 19 01:02:42 2017 -0400
+++ b/mercurial/revlog.py	Sun Mar 19 01:05:28 2017 -0400
@@ -117,7 +117,7 @@
 def offset_type(offset, type):
     if (type & ~REVIDX_KNOWN_FLAGS) != 0:
         raise ValueError('unknown revlog index flags')
-    return long(long(offset) << 16 | type)
+    return int(int(offset) << 16 | type)
 
 _nullhash = hashlib.sha1(nullid)