* tests/extrac07.at, tests/extrac09.at, tests/listed03.at: Use
AT_UNPRIVILEGED_PREREQ, since this test requires non-root
privileges.
* tests/extrac07.at: Don't use "chmod -w", as POSIX says it's not
portable to start a chmod permissions-list with "-" as it may be
confused with an option. Use "chmod a-w" instead.
* src/misc.c (struct wd): Rename 'saved' to 'err', with new semantics.
(chdir_arg, chdir_do): Adjust to new semantics. Do not report an
error merely because save_cwd fails; report an error only if
save_cwd's result is needed later.
* tests/extrac09.at: New file, to test for bug that was fixed.
* tests/testsuite.at: Include it.
* tests/Makefile.am (TESTSUITE_AT): Add it.
