rustc_codegen_ssa: add s390x_target_feature symbol

Author: liushuyu

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -80,6 +80,7 @@ pub fn from_target_feature(
                 Some(sym::loongarch_target_feature) => rust_features.loongarch_target_feature,
                 Some(sym::lahfsahf_target_feature) => rust_features.lahfsahf_target_feature,
                 Some(sym::prfchw_target_feature) => rust_features.prfchw_target_feature,
+                Some(sym::s390x_target_feature) => rust_features.s390x_target_feature,
                 Some(name) => bug!("unknown target feature gate {}", name),
                 None => true,
             };

compiler/rustc_feature/src/unstable.rs

@@ -310,6 +310,7 @@ declare_features! (
     (unstable, prfchw_target_feature, "1.78.0", Some(44839)),
     (unstable, riscv_target_feature, "1.45.0", Some(44839)),
     (unstable, rtm_target_feature, "1.35.0", Some(44839)),
+    (unstable, s390x_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
     (unstable, sse4a_target_feature, "1.27.0", Some(44839)),
     (unstable, tbm_target_feature, "1.27.0", Some(44839)),
     (unstable, wasm_target_feature, "1.30.0", Some(44839)),