Fix Issue 19796 - wrong assumption of integral element type

[wilzbach]

I didn't know any better way to do this, so better ideas are very welcome!

[dlang-bot]

Thanks for your pull request, @wilzbach!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	19796	regression	druntime PR#1982 broke array ops on double[] due to wrong assumption of integral element type

⚠️⚠️⚠️ Warnings ⚠️⚠️⚠️

• Regression or critical bug fixes should always target the stable branch. Learn more about rebasing to stable or the D release process.

To target stable perform these two steps:

1. Rebase your branch to upstream/stable:

git rebase --onto upstream/stable upstream/master

2. Change the base branch of your PR to stable

Testing this PR locally

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

dub fetch digger
dub run digger -- build "master + druntime#2550"

[wilzbach]

Regression or critical bug fixes should always target the stable branch.

Regression is in master only.

[quickfur]

Thanks!