rustc_target: Add msync target feature and enable it on powerpcspe targets

Author: taiki-e

Diff for: compiler/rustc_target/src/spec/targets/powerpc_unknown_linux_gnuspe.rs

@@ -24,7 +24,7 @@ pub(crate) fn target() -> Target {
         options: TargetOptions {
             abi: "spe".into(),
             endian: Endian::Big,
-            features: "+secure-plt".into(),
+            features: "+secure-plt,+msync".into(),
             mcount: "_mcount".into(),
             ..base
         },

Diff for: compiler/rustc_target/src/spec/targets/powerpc_unknown_linux_muslspe.rs

@@ -26,6 +26,7 @@ pub(crate) fn target() -> Target {
         options: TargetOptions {
             abi: "spe".into(),
             endian: Endian::Big,
+            features: "+msync".into(),
             mcount: "_mcount".into(),
             ..base
         },

Diff for: compiler/rustc_target/src/target_features.rs

@@ -461,6 +461,7 @@ const HEXAGON_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
 static POWERPC_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
     ("altivec", Unstable(sym::powerpc_target_feature), &[]),
+    ("msync", Unstable(sym::powerpc_target_feature), &[]),
     ("partword-atomics", Unstable(sym::powerpc_target_feature), &[]),
     ("power10-vector", Unstable(sym::powerpc_target_feature), &["power9-vector"]),
     ("power8-altivec", Unstable(sym::powerpc_target_feature), &["altivec"]),

Diff for: tests/ui/check-cfg/target_feature.stderr

@@ -151,6 +151,7 @@ LL |     cfg!(target_feature = "_UNEXPECTED_VALUE");
 `mp`
 `mp1e2`
 `msa`
+`msync`
 `mte`
 `multivalue`
 `mutable-globals`