Fix issue 19639

[dhasenan]

When doing a reinterpret cast on a string literal to a static array, ensure the static array has enough capacity.

This is a minimal bandaid fix for issue 19639. It changes the behavior of a construct that has been broken at least since 2015, from giving garbage data to a compile-time error. It also fixes a segfault.

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	19639	regression	Initializing static array with slice enum of different length crashes the compiler

⚠️⚠️⚠️ 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 + dmd#9317"