Rollup merge of #144143 - Gelbpunkt:target-features-crt-static, r=RalfJung

Fix `-Ctarget-feature`s getting ignored after `crt-static`

The current behaviour introduced by commit a50a3b8e318594c41783294e440d864763e412ef would discard any target features specified after `crt-static` (the only member of `RUSTC_SPECIFIC_FEATURES`). This is because it returned instead of continuing processing the next feature.

I wasn't entirely sure how the regression test should look like, but this one should do. If anyone has some suggestions, I'm happy to learn, it's my first test :)

I've confirmed that the test fails without the fix on `powerpc64le-unknown-linux-musl` and `x86_64-unknown-linux-gnu`.

cc ``@RalfJung``

Author: GuillaumeGomez