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 a50a3b8e31 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``

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -149,14 +149,14 @@ fn parse_rust_feature_flag<'a>(
         if let Some(base_feature) = feature.strip_prefix('+') {
             // Skip features that are not target features, but rustc features.
             if RUSTC_SPECIFIC_FEATURES.contains(&base_feature) {
-                return;
+                continue;
             }
 
             callback(base_feature, sess.target.implied_target_features(base_feature), true)
         } else if let Some(base_feature) = feature.strip_prefix('-') {
             // Skip features that are not target features, but rustc features.
             if RUSTC_SPECIFIC_FEATURES.contains(&base_feature) {
-                return;
+                continue;
             }
 
             // If `f1` implies `f2`, then `!f2` implies `!f1` -- this is standard logical