[MacPorts] #57036: GTK3 patch to compile on 10.5 and 10.6

[MacPorts]

#57036: GTK3 patch to compile on 10.5 and 10.6
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 Reporter:  rmottola                  |      Owner:  (none)
     Type:  defect                    |     Status:  new
 Priority:  Normal                    |  Milestone:
Component:  ports                     |    Version:
 Keywords:  gtk3 Leopard SnowLeopard  |       Port:  gtk3
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 attached patch to get GTK3 compiling on 10.5 and 10.6

 result tested on 10.6 with GIMP 2.10 which now completes build runs and
 appears usable enough. GIMP 2.10 does not build yet on 10.5 so provided
 "as is" for other purposes.

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Ticket URL: <https://trac.macports.org/ticket/57036>
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