[MacPorts] #55879: cargo: add universal variant

[MacPorts]

#55879: cargo: add universal variant
-------------------------+------------------------
 Reporter:  ryandesign   |      Owner:  seanfarley
     Type:  enhancement  |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:
 Keywords:               |       Port:  cargo
-------------------------+------------------------
 librsvg has problems building its latest version universal because it now
 requires cargo and cargo does not have a universal variant.

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Ticket URL: <https://trac.macports.org/ticket/55879>
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