I think that the trailing __ got added in false analogy to
HAVE_MACRO__func__, HAVE_MACRO__FUNC__, and HAVE_MACRO__FUNCTION__.
But those macros actually indicate the presence of __func__,
__FUNC__, and __FUNCTION__ respectively. The __ at the end of
HAVE_EXTERN_ENVIRON_DECLARED would only be appropriate if the
environ were declared__, whatever that means.
(As a side-note, HAVE_MACRO__func__ and so on should probably be
renamed HAVE_MACRO___func__ and so on. But that can wait.)
This is an identifier renaming only.
Nick Mathewson
c03a233faa