Fix issue 21234: Import expression can read files outside of -J path in case of symlink/hardlink

[andrey-zherikov]

This change make import expression (import("...")) to work on Posix the same way as it works on Windows.

The original code tries to resolve symlinks on Posix and rejects a file if its real path is outside of -J options (although hardlinks pointing outside of -J are allowed).

This approach has the following issues:

• It doesn't allow the use case where -J directory has symlinks to cherry-picked files from other places (hardlinks and/or copying of files are not always possible).
• Different behavior on Posix vs. Windows.

From the other side, providing -J option to compiler means explicit consent to use the content of -J directory regardless of the type of this content (regular file/symlink/pipe etc).

See https://issues.dlang.org/show_bug.cgi?id=21234 for more details.

[MoonlightSentinel]

Please add a test case

[dlang-bot]

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21234	normal	Import expression can read files outside of -J path in case of symlink/hardlink

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 + dmd#11836"

[andrey-zherikov]

Please add a test case

Done.

[andrey-zherikov]

Sorry, rebase didn't work the way I expected so I re-applied my changes on top of master and force-pushed them.

test added