libcxx @5.0.1_1+universal: upgrade failure on Leopard

[potmj (Michael Pot)]

After successfully building libcxx @5.0.1_0+universal, as part of slowly working through ​https://trac.macports.org/wiki/LibcxxOnOlderSystems, further ports now want to upgrade the libcxx dependent.

port -v installed libcxx
The following ports are currently installed:
  libcxx @3.9.1_0-universal platform='darwin 9' archs='i386' date='2017-09-09T16:36:04+1200'
  libcxx @3.9.1_1-universal platform='darwin 9' archs='i386' date='2017-12-28T01:13:04+1300'
  libcxx @5.0.1_0-universal platform='darwin 9' archs='i386' date='2017-12-30T09:05:22+1300'
  libcxx @5.0.1_0+universal (active) platform='darwin 9' archs='i386 ppc x86_64' date='2018-01-09T09:07:46+1300'

It looks like +universal is now inserting whole lot of gcc unsupported options like:-

cc1plus: error: unrecognized command line option "-std=c++11"
cc1plus: error: unrecognized command line option "-stdlib=libc++"

I can't see why @5.0.1_0 worked, & @5.0.1_1 does not. I think I have wound back all the macports.conf changes correctly, so don't see why it is asking for -stdlib=libc++ with Xcode gcc (e.g. have commented out with #cxx_stdlib libc++).

[potmj (Michael Pot)]

Leopard port -v upgrade libcxx