[MacPorts] #70184: gtk3 +quartz missing a build dependency on mesa

[MacPorts]

#70184: gtk3 +quartz missing a build dependency on mesa
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  Reporter:  bll123           |      Owner:  mascguy
      Type:  defect           |     Status:  assigned
  Priority:  Normal           |  Milestone:
 Component:  ports            |    Version:  2.9.3
Resolution:                   |   Keywords:
      Port:  gtk3 gtk3-devel  |
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Comment (by thomasrussellmurphy):

 I'm using +quartz, but also needed to manually install mesa to progress on
 the build for the latest gtk3 update.

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Ticket URL: <https://trac.macports.org/ticket/70184#comment:4>
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