[Bug libstdc++/56109] Add light-weight ABI-compatible debug checks to standard containers

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56109

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
As of r227595 trunk now supports a _GLIBCXX_ASSERTIONS macro that enables
lightweight checks. We will start merging some of the __google_stl checks to
trunk and enabling them with that macro (which might give you a number of merge
conflicts on your branch, sorry!)