Update to 2.24

Changelog:
* Noteworthy changes in release 2.24 (2016-03-10) [stable]

** Bug fixes

  grep -z would match strings it should not.  To trigger the bug, you'd
  have to use a regular expression including an anchor (^ or $) and a
  feature like a range or a backreference, causing grep to forego its DFA
  matcher and resort to using re_search.  With a multibyte locale, that
  matcher could mistakenly match a string containing a newline.
  For example, this command:
    printf 'a\nb\0' | LC_ALL=en_US.utf-8 grep -z '^[a-b]*b'
  would mistakenly match and print all four input bytes.  After the fix,
  there is no match, as expected.
  [bug introduced in grep-2.7]

  grep -Pz now diagnoses attempts to use patterns containing ^ and $,
  instead of mishandling these patterns.  This problem seems to be
  inherent to the PCRE API; removing this limitation is on PCRE's
  maint/README wish list.  Patterns can continue to match literal ^
  and $ by escaping them with \ (now needed even inside [...]).
  [bug introduced in grep-2.5]


(ryoon)