[pushed] libstdc++, Darwin: Fix weak attribute to use __weak__ instead of weak.

[Jonathan Wakely]

On Sun, 4 Dec 2022, 10:54 Iain Sandoe via Libstdc++, <libstdc++@gcc.gnu.org>
wrote:

> As pointed out on irc by Jonathan, the Darwin os_defines contains a "weak"
> attribute where we should use '__weak__'.  Fixed thus, tested on i686,
> x86_64
> Darwin and x86_64 Linux, pushed to master, thanks,
> Iain


> -- >8 --
>

I wanted to be sure this wouldn't conflict with the __weak keyword for
obj-C so thanks for taking care of it.