[MacPorts] #48775: rust: update to 1.2.0

[MacPorts]

#48775: rust: update to 1.2.0
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 Reporter:  sean@…    |      Owner:  g5pw@…
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  ports     |    Version:  2.3.3
 Keywords:  haspatch  |       Port:
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 I've been looking at rust and thought I'd upgrade it to 1.2.0. I think the
 bootstrapping is no longer needed since version 1.0 (the one we were using
 was old as well). Here is a patch for removing the bootstrapping code and
 preferring clang. Since I'm new to rust, I was hoping someone could give
 this a once over.

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Ticket URL: <https://trac.macports.org/ticket/48775>
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