Rollup merge of #122790 - Zoxc:dllimp-rev, r=ChrisDenton

Apply dllimport in ThinLTO

This partially reverts rust-lang/rust#103353 by properly applying `dllimport` if  `-Z dylib-lto` is passed. That PR should probably fully be reverted as it looks quite sketchy. We don't know locally if the entire crate graph would be statically linked.

This should hopefully be sufficient to make ThinLTO work for rustc on Windows.

r? ``@wesleywiser``

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Edit: This PR is changed to just generally revert rust-lang/rust#103353.

Author: matthiaskrgr