[patch] libstdc++/67173 Fix filesystem::canonical for Solaris 10.

[Jonathan Wakely]

On 16/09/15 17:02 +0100, Jonathan Wakely wrote:
>I don't know how to use _XOPEN_VERSION or _POSIX_VERSION to check for
>a suitable realpath without defining one of those feature-test macros,
>which then breaks other things.

I suppose we could also define _NETBSD_SOURCE manually, which is
basically what we do on GNU/Linux. G++ predefines _GNU_SOURCE so that
glibc gives us all declarations, but I want to move away from that and
stop polluting the global namespace with every GNU extension.

Maybe defining _NETBSD_SOURCE for versions older than 7.x is the right
solution though.