octave @4.4.1: error: field has incomplete type 'const cdef_class'

[ryandesign (Ryan Carsten Schmidt)]

​https://build.macports.org/builders/ports-10.9_x86_64-builder/builds/68065/steps/install-port/logs/stdio

  CXX      libinterp/corefcn/libinterp_corefcn_libcorefcn_la-colloc.lo
In file included from libinterp/corefcn/bsxfun.cc:28:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/list:174:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/memory:598:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/utility:253:9: error: field has incomplete type 'const cdef_class'
    _T1 first;
        ^

I see that it's building with Xcode clang 600.0.57, despite the fact that the Portfile blacklists {clang < 700}. This is probably because in [aec14792b8457e3c77b5c90a3c402a88ba9eb41b/macports-ports] the blacklist is getting reset to just macports-gcc-6. I'm sure this was meant to append to the blacklist instead of overwriting it.

[ryandesign (Ryan Carsten Schmidt)]

In 323ed0baa87267c3507ddbad48f4202eac52b6a1/macports-ports (master):

octave: Append to blacklist instead of overwriting

Closes: #57269

[MarcusCalhoun-Lopez (Marcus Calhoun-Lopez)]

Thank you for fixing this problem.