Fix performance regression introduced by PR #7285.

[ghost]

The global import of std.math : FloatingPointControl caused a performance regression. This PR fixes this by making the import local.

See discussion for more details.

PS: I checked, using valgrind, that this import indeed caused the regression.

[dlang-bot]

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If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

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 "stable + phobos#7346"

[kinke]

This loosens Phobos intra-dependencies again and is much appreciated; e.g., this previously broke usability of std.algorithm.* stuff for WebAssembly.

[ghost]

Wow, never had a PR with 3 approvals. ;-) Unfortunately the tests got stuck, both just not returning the positive result, as far as I can see...