New submission from Aidan Hobson Sayers:
Posix says the following on the subject of getenv:
The returned string pointer might be invalidated or the string content might
be overwritten by a subsequent call to getenv()
(http://pubs.opengroup.org/onlinepubs/9699919799/functions/getenv.html
Aidan Hobson Sayers added the comment:
In case it matters, I'm compiling using Emscripten which implements getenv like
so: https://github.com/kripken/emscripten/blob/1.25.2/src/library.js#L3323
(I personally think it's a bizarre way to do it, but technically I think it's
ok
