added non-poison mutex

Author: Aandreba

library/std/src/sync/nonpoison/mutex.rs

@@ -219,7 +219,13 @@ impl<T: ?Sized> Mutex<T> {
     /// ```
     #[unstable(feature = "nonpoison_mutex", issue = "134645")]
     pub fn try_lock(&self) -> Option<MutexGuard<'_, T>> {
-        unsafe { if self.inner.try_lock() { Some(MutexGuard::new(self)) } else { None } }
+        unsafe {
+            if self.inner.try_lock() {
+                Some(MutexGuard::new(self))
+            } else {
+                None
+            }
+        }
     }
 
     /// Consumes this mutex, returning the underlying data.