libstdc++ testsuite regressions

[David Edelsohn]

>>>>> Paolo Carlini writes:

Paolo> Does the below help? Otherwise something is very misteriously broken
Paolo> wrt  _GLIBCXX_HAVE_SETENV...

	cstdlib already is included via stdc++.h.  That is not the
problem.

	The problem is that setenv() only is present in stdlib.h with
XOPEN 6.  I will change the GCC AIX configuration to define the right
macro and see if that helps.

	However, libstdc++ cstdlib refers to getenv but not to setenv.
The testcase works without that addition, but I am not sure if that is
correct.  However because of the weird XOPEN changes, adding that might
break some targets.

David