[MacPorts] #55264: libressl @2.5.5: update to 2.6.4

[MacPorts]

#55264: libressl @2.5.5: update to 2.6.4
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  Reporter:  l2dy      |      Owner:  jeremyhu
      Type:  update    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:
      Port:  libressl  |
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Comment (by janstary):

 I don't think https://trac.macports.org/ticket/54744 prevents us from
 upgrading LibreSSL.
 Reading the release notes since 2.6.2 (which we curently have in libressl-
 devel) up to 2.7.2,
 there are changes we definitely want to have. Cherrypicking these two:

 * Added support for many OpenSSL 1.0.2 and 1.1 APIs, based on observations
 of real-world usage in applications.
 * Fixed builds macOS 10.11 and older.

 I believe we have much better reasons to upgrade than not to upgrade.

-- 
Ticket URL: <https://trac.macports.org/ticket/55264#comment:7>
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