Auto merge of #88002 - hermitcore:unbox-mutex, r=dtolnay

Unbox mutexes, condvars and rwlocks on hermit

[RustyHermit](https://github.com/hermitcore/rusty-hermit) provides now movable synchronization primitives and we are able to unbox mutexes and condvars.

Cargo.lock

@@ -1529,9 +1529,9 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.1.17"
+version = "0.1.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5aca5565f760fb5b220e499d72710ed156fdb74e631659e99377d9ebfbd13ae8"
+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
 dependencies = [
  "compiler_builtins",
  "libc",

library/std/Cargo.toml

@@ -42,7 +42,7 @@ dlmalloc = { version = "0.2.1", features = ['rustc-dep-of-std'] }
 fortanix-sgx-abi = { version = "0.3.2", features = ['rustc-dep-of-std'] }
 
 [target.'cfg(all(any(target_arch = "x86_64", target_arch = "aarch64"), target_os = "hermit"))'.dependencies]
-hermit-abi = { version = "0.1.17", features = ['rustc-dep-of-std'] }
+hermit-abi = { version = "0.1.19", features = ['rustc-dep-of-std'] }
 
 [target.wasm32-wasi.dependencies]
 wasi = { version = "0.9.0", features = ['rustc-dep-of-std'], default-features = false }

library/std/src/sys/hermit/condvar.rs

@@ -14,7 +14,7 @@ pub struct Condvar {
     sem2: *const c_void,
 }
 
-pub type MovableCondvar = Box<Condvar>;
+pub type MovableCondvar = Condvar;
 
 unsafe impl Send for Condvar {}
 unsafe impl Sync for Condvar {}

library/std/src/sys/hermit/mutex.rs

@@ -156,7 +156,7 @@ pub struct Mutex {
     inner: Spinlock<MutexInner>,
 }
 
-pub type MovableMutex = Box<Mutex>;
+pub type MovableMutex = Mutex;
 
 unsafe impl Send for Mutex {}
 unsafe impl Sync for Mutex {}

library/std/src/sys/hermit/rwlock.rs

@@ -8,7 +8,7 @@ pub struct RWLock {
     state: UnsafeCell<State>,
 }
 
-pub type MovableRWLock = Box<RWLock>;
+pub type MovableRWLock = RWLock;
 
 enum State {
     Unlocked,