getcwd: fix test failure on OS X 10.9
* m4/getcwd-path-max.m4: Avoid the replacement if it
won't be effective due to the PATH_MAX limitation of lstat().
(gl_cv_func_getcwd_path_max): Adjust to indicate this case.
* m4/getcwd.m4 (gl_FUNC_GETCWD): Define HAVE_GETCWD_SHORTER
for this case for use in tests, and also exclude this
case when setting REPLACE_GETCWD.
* tests/test-getcwd.c (test_long_name): Restrict the
tested path length so that lstat() will not be passed
a path greater than PATH_MAX.
Also key a test condition on HAVE_OPENAT_SUPPORT rather
than AT_FDCWD, since the latter is set unconditionally
since Sep 2009 in commit
52c658e9.