[MacPorts] #56294: boost: update to 1.70.0

[MacPorts]

#56294: boost: update to 1.70.0
------------------------+---------------------------------
  Reporter:  michaelld  |      Owner:  ryandesign
      Type:  update     |     Status:  assigned
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:
Resolution:             |   Keywords:  haspatch maintainer
      Port:  boost      |
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Comment (by cjones051073):

 Could I suggest it would be very useful to do something similar to the on
 going openssl 1.1.x update here, so push your changes to a WIP github PR
 and also start to revbump dependents as required.

 https://github.com/macports/macports-ports/pull/3822

 I think that would make it much easier for others to review and test (I
 personally am not going to faff about downloading and installing patches
 by hand, but if its a branch in github thats a different story).

 I would also suggest aiming for perfection here is counter productive. We
 should aim to fix things as far as is reasonable, but at some point just
 merge the changes, and deal with whatever that causes.

-- 
Ticket URL: <https://trac.macports.org/ticket/56294#comment:25>
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