> system C/C++ ABI
C++ abi should not be included in this. It is independent from the other pieces and historically a source of incompatibility on its own.
Saying "C/C++ abi" as if they are the same is looney tunes, the former is very simple and stable and the latter is very complex.
See: https://news.ycombinator.com/item?id=49355262
How libstdc++ initializes global variables absolutely depends on glibc and ld-linux.so. That is part of C++ ABI.