Fix Issue 21853 - std.format: formatting real.max in CTFE fails

[berni44]

A copy of #8001. The bot had not noticed my forced push, so I tried to restart the testers with closing and reopening, but I'm not allowed to reopen now, because there are forced pushes...

I had to remove windows from the unittest due to issed 20972, hence to forced push.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21853	normal	std.format: formatting real.max in CTFE fails

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#8002"

[berni44]

Found a way around the windows bug. That's better, because now it fixes the issue also for those computers.

[berni44]

This is good to go now. phew