[Bug libstdc++/36231] ostream includes unistd.h outside namespace std, polluting

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36231

--- Comment #18 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-04-21 00:02:02 UTC ---
Thanks Ralf, I didn't know AC_CHECK_SIZEOF and AC_CHECK_ALIGNOF even existed,
in similar situations probably I would have dumbly re-invented both basing on
AC_COMPUTE_INT ;)

Otherwise, about the issue which prompted my question, seems still tough,
because actually gthr.h is included by a few different headers, also in locale,
not just via the path explained in the PR. Frankly, I don't know how much we
can get into this within the existing ABI... To Ivan I have to remember that we
don't control in general the underlying .h headers, it's the usual question,
how far we can go without assuming much about the C headers and of course
without changing the headers themselves...