_GLIBCXX_USE_CXX11_ABI

[Iain Hibbert <plunky%ogmig.net@localhost>]

Hi

when I added the cad/solvespace package earlier this year, I needed to add

  -D_GLIBCXX_USE_CXX11_ABI=0

to the CXXFLAGS to get it to build (I don't remember exactly what version 
of NetBSD I was on; perhaps still 7.99.x at that time). However, now it 
fails to build with that (8.99.7) but is ok if I remove it.

I can't see that this has caused any problems in the bulk build reports 
though some are CLANG and some are older NetBSD. The issue is apparently 
explained here:

  https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html

and I think NetBSD perhaps had a bit of churn with gcc/libstdc++ updating 
around that time (I'm using gcc 5.4.0 now at least, on a reasonably 
current system) and is perhaps now stable

is there a canonical way to deal with this?  I don't see this flag being 
used anywhere else in my checked out pkgsrc tree..

iain