[MacPorts] #56294: boost: update to 1.70.0

[MacPorts]

#56294: boost: update to 1.70.0
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  Reporter:  michaelld  |      Owner:  ryandesign
      Type:  update     |     Status:  assigned
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:
Resolution:             |   Keywords:  haspatch maintainer
      Port:  boost      |
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Changes (by michaelld):

 * cc: cjones051073 (removed)


Comment:

 OK I have a WIP PR for testing < https://github.com/macports/macports-
 ports/pull/4243 >. In my testing thus far, it works very well overall,
 with the primary -port- issue being the MPI variant, which fails in
 destroot & I'm not sure how to fix it yet. Please test / verify & report
 back successes / failures!

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Ticket URL: <https://trac.macports.org/ticket/56294#comment:28>
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