[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 neumann@…):

 The upstream maintainer is for some unknown reasons very reluctant to
 release new versions. Also the conservative ebian switched to a date-based
 git checkout for debian for that reason. However, for the time being, i
 see no strong reason for requiring the other changes. The real source for
 this repository is fossil, the mirroring to github seems as well flaky.
 However, I've added the time being the 2 portgroup lines, and it seems to
 work still fine.... and uploaded more more diff.

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Ticket URL: <https://trac.macports.org/ticket/49359#comment:5>
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