[cfe-dev] Oldest supported libstdc++

[Nathan Sidwell via cfe-dev]

I came across a couple of clang workarounds for old libstdc++ issues. 
One of them seems good for removal, by documenting the oldest supported 
libstdc++ as 4.9, which is what https://reviews.llvm.org/D100465 does.

The other is more recent, and proposing to keep that (see 
https://reviews.llvm.org/D100469)

any objections on the oldest libstdc++ version?

nathan

-- 
Nathan Sidwell