[MacPorts] #49359: tdom: fix build failure with tcl 8.6

[MacPorts]

#49359: tdom: fix build failure with tcl 8.6
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  Reporter:  neumann@…  |      Owner:  ryandesign@…
      Type:  defect     |     Status:  assigned
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:  2.3.4
Resolution:             |   Keywords:  haspatch maintainer
      Port:  tdom       |
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Comment (by ss@…):

 A working tdom port would greatly ease macports-based deployment of my Tcl
 apps.

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Ticket URL: <https://trac.macports.org/ticket/49359#comment:11>
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