[v3] Handle different versions of Solaris 8 <iso/math_iso.h>, <iso/stdlib_iso.h>

[Paolo Carlini]

Hi,

> I'm pretty sure this is the case for Solaris.  The other changes we've
> made to support __cplusplus 199711L were no-ops without the last one to change __cplusplus from 1 to the C++ 98 value.  So, redefining
> __cplusplus to 1 should return us back to the old status.

I see, then I think the patch is Ok. Since you are so well positioned to test on Solaris machines, I would recommend running the library testsuite with -D__cplusplus=1 added to CXXFLAGS, as a final check.

Paolo