[MacPorts] #67742: PothosFlow: builds fail across-the-board: undefined symbols related to libcxx: allocator<>, basic_string<>, etc

[MacPorts]

#67742: PothosFlow: builds fail across-the-board: undefined symbols related to
libcxx: allocator<>, basic_string<>, etc
-------------------------+--------------------------
  Reporter:  mascguy     |      Owner:  barracuda156
      Type:  defect      |     Status:  assigned
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.8.1
Resolution:              |   Keywords:
      Port:  PothosFlow  |
-------------------------+--------------------------

Comment (by barracuda156):

 Replying to [comment:3 mascguy]:
 > Sergey, can you kindly submit a PR ASAP, with the build fix?

 So perhaps change the owner to someone who can deal with the matter? I am
 pretty sure it is not me breaking it, and it is easy to check for someone
 whose environment has Qt5 and all: drop GCC patch from `PothosCore`,
 rebuild, and see if `PothosFlow` builds. I believe the result should be
 strictly identical with and without my GCC patch, as long as Clang is
 used.

-- 
Ticket URL: <https://trac.macports.org/ticket/67742#comment:6>
MacPorts <https://www.macports.org/>
Ports system for macOS