Check for chmod, hardlink, symlink, and special character support to
prevent test suite failures in feature constrained environments.
Thanks to Bruno Haible and Nelson H. F. Beebe for their testing and
analysis.
* tests/test-lib.sh: Add new feature tests.
* tests/hardlinks: Split this hardlinks related test off from
tests/remember-backup-files.
* tests/Makefile.am (TESTS): Add new hardlinks test here.
* tests/file-create-modes, tests/file-modes, tests/read-only-files,
tests/preserve-mode-and-timestamp, tests/no-mode-change-git-diff: These
tests require chmod support.
* tests/hardlinks, tests/unmodified-files: These tests require hardlink
support.
* tests/symlinks: This test requires symlink support.
* tests/quoted-filenames: This test requires special character support
in filenames.
