tests/test-empty-dir.t

tests: add glob matching for unified tests

This adds a " (glob)" marker that works like a simpler version of
(re): "*" is converted to ".*", and "?" is converted to ".".

Both special characters can be escaped using "\", and the backslash
itself can be escaped as well.

Other glob-style syntax, like "**", "[chars]", or "[!chars]", isn't
supported.

  $ hg init

  $ echo 123 > a
  $ hg add a
  $ hg commit -m "first" a

  $ mkdir sub
  $ echo 321 > sub/b
  $ hg add sub/b
  $ hg commit -m "second" sub/b

  $ cat sub/b
  321

  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cat sub/b 2>/dev/null || echo "sub/b not present"
  sub/b not present

  $ test -d sub || echo "sub not present"
  sub not present