[MacPorts] #58919: fontforge build failure on 10.7.5

[MacPorts]

#58919: fontforge build failure on 10.7.5
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  Reporter:  lemzwerg   |      Owner:  (none)
      Type:  defect     |     Status:  new
  Priority:  Normal     |  Milestone:
 Component:  ports      |    Version:
Resolution:             |   Keywords:  lion
      Port:  fontforge  |
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Comment (by jmroot):

 2.6 will still try the system clang if it can use the selected stdlib. So
 on 10.7 and later, more or less.

 Here, _Noreturn is a C11 feature, so it should at least be using the
 appropriate -std= option. Compilers that don't support C11 also need to be
 excluded. With 2.6 we could just set compiler.c_standard, but for now we
 just have to do some blacklisting.

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Ticket URL: <https://trac.macports.org/ticket/58919#comment:5>
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