Re: infer GCC_REQD from USE_LANGUAGES (was: nghttp2 broken)

[maya%netbsd.org@localhost]

I think the way to go forward is,

- Add a test to see if the previous libstdc++ is built with ABI compat
(NetBSD as of 8.0 and most linux distros effectively had a major bump)

- Do a better job of mirroring the major number of libstdc++
I have sed thing to change it to 7.x, but NetBSD has since bumped it
again.

- Declare one GCC to be the one override GCC, if the existing one is
  insufficient.
I've been reluctant to do this, because I know it's good for me in
NetBSD, but I don't know what it means for people who use just pkgsrc
GCC.

GCC 7 or 8 will be good.


that is, try to create libstdc++ from pkgsrc to be as compatible as
possible. At least compare the output of `nm --defined-only` between
them to see if it is the same and try to reach it.