Backport 1.51 and 1.54 from trunk.

Backport 1.51 and 1.54 from trunk.

1.51:
Bug #556025: list(xrange(1e9)) --> seg fault

Close the bug report again -- this time for Cygwin due to a newlib bug.
See the following for the details:

	http://sources.redhat.com/ml/newlib/2002/msg00369.html

Note that this commit is only a documentation (i.e., comment) change.

1.54:
The list(xrange(sys.maxint / 4)) test blew up on 64-bit platforms.
Because ob_size is a 32-bit int but sys.maxint is LONG_MAX which is a
64-bit value, there's no way to make this test succeed on a 64-bit
platform.  So just skip it when sys.maxint isn't 0x7fffffff.