[MacPorts] #55163: supertux: Update to version 0.5.1

[MacPorts]

#55163: supertux: Update to version 0.5.1
-----------------------+-----------------
  Reporter:  mf2k      |      Owner:
      Type:  update    |     Status:  new
  Priority:  Normal    |  Milestone:
 Component:  ports     |    Version:
Resolution:            |   Keywords:
      Port:  supertux  |
-----------------------+-----------------

Comment (by mf2k):

 Here is the configure error:
 {{{
 :info:configure -- Looking for PHYSFS_getPrefDir - not found
 :info:configure CMake Error at CMakeLists.txt:185 (message):
 :info:configure   physfs submodule is not checked out or
 :info:configure
 /opt/local/var/macports/build/_opt_local_var_macports_sources_github
 .com_macports_macports-ports_games_supertux/supertux/work/SuperTux-
 supertux-e2ecf3c/external/physfs/CMakeLists.txt
 :info:configure   is missing
 :info:configure -- Configuring incomplete, errors occurred!
 }}}

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Ticket URL: <https://trac.macports.org/ticket/55163#comment:1>
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