Fix build two build problems.

* Didn't pass the portability check, noted by joerg@.
* Some PLIST problem.

No bump revision since the package was broken.
libXext build failure on OpenBSD exposed libX11 test failing during
configure due to missing pthread library. Buildlink pthread. Don't hardcode
-pthread for OSF1, MirBSD, and OpenBSD, but use PTHREAD_{C,LD}FLAGS
instead. Add pthread in bl3, but for the above targets.
Changes 2.19:
** Improvements

  Performance has improved, typically by 10% and in some cases by a
  factor of 200.  However, performance of grep -P in UTF-8 locales has
  gotten worse as part of the fix for the crashes mentioned below.

** Bug fixes

  grep no longer mishandles patterns like [a-[.z.]], and no longer
  mishandles patterns like [^a] in locales that have multicharacter
  collating sequences so that [^a] can match a string of two characters.

  grep no longer mishandles an empty pattern at the end of a pattern list.
  [bug introduced in grep-2.5]

  grep -C NUM now outputs separators consistently even when NUM is zero,
  and similarly for grep -A NUM and grep -B NUM.
  [bug present since "the beginning"]

  grep -f no longer mishandles patterns containing NUL bytes.
  [bug introduced in grep-2.11]

  Plain grep, grep -E, and grep -F now treat encoding errors in patterns
  the same way the GNU regular expression matcher treats them, with respect
  to whether the errors can match parts of multibyte characters in data.
  [bug present since "the beginning"]

  grep -w no longer mishandles a potential match adjacent to a letter that
  takes up two or more bytes in a multibyte encoding.
  Similarly, the patterns '\<', '\>', '\b', and '\B' no longer
  mishandle word-boundary matches in multibyte locales.
  [bug present since "the beginning"]

  grep -P now reports an error and exits when given invalid UTF-8 data.
  Previously it was unreliable, and sometimes crashed or looped.
  [bug introduced in grep-2.16]

  grep -P now works with -w and -x and backreferences. Before,
  echo aa|grep -Pw '(.)\1' would fail to match, yet
  echo aa|grep -Pw '(.)\2' would match.

  grep -Pw now works like grep -w in that the matched string has to be
  preceded and followed by non-word components or the beginning and end
  of the line (as opposed to word boundaries before).  Before, this
  echo a@@a| grep -Pw @@ would match, yet this
  echo a@@a| grep -w @@ would not.  Now, they both fail to match,
  per the documentation on how grep's -w works.

  grep -i no longer mishandles patterns containing titlecase characters.
  For example, in a locale containing the titlecase character
  'ǈ' (U+01C8 LATIN CAPITAL LETTER L WITH SMALL LETTER J),
  'grep -i ǈ' now matches both 'Ǉ' (U+01C7 LATIN CAPITAL LETTER LJ)
  and 'ǉ' (U+01C9 LATIN SMALL LETTER LJ).
Changes 0.7.6:
Fixed Solaris & Solaris Studio support and Python 2.6 compatibility.
Updated textproc/grep to 2.19; sysutils/py-xattr to 0.7.6
Disable Quartz backend on Darwin

Quartz backend interacts badly with our library stack. The most notable
issue is that when quartz-font is enabled, cairo will never use fontconfig
but instead uses CoreGraphics API to find fonts in system-default font
paths; as a result, any fonts installed with pkgsrc will never be found.
OTOH fontconfig by default searches for fonts in MacOS X system-default
paths too so sticking with it will not cause a problem.
Darwin: pangocoretext.h is no longer installed because cairo-quartz is now disabled.
Darwin: cairomm-quartz is no longer installed because cairo-quartz is now disabled.
Be a bit more friendly toward libc++.
Fix build with clang.
Redo -ldl handling. Be nicer to libc++.
Add forgotten patch for libc++ build.
Avoid two tautological checks.
Fix static member defines. Fix build with newer Freetype.
Declare build system correctly.
Fix build against newer libguardtime.