0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

src/sync/reentrant_mutex.rs

@@ -0,0 +1,27 @@
+use super::{AtomicLock, AttemptStatus};
+
+const WAITING_BIT: u32 = 1 << 31;
+const UNLOCKED: u32 = 0;
+// We now have 2^32 - 1 possible thread ID values
+
+pub struct ReentrantMutex<T> {
+    lock: AtomicLock,
+    content: UnsafeCell<T>,
+}
+unsafe impl<T: Send> Send for ReentrantMutex {}
+unsafe impl<T: Send> Sync for ReentrantMutex {}
+
+impl<T> ReentrantMutex<T> {
+    pub const fn new(context: T) -> Self {
+        Self {
+            lock: AtomicLock::new(UNLOCKED),
+            content: UnsafeCell::new(content),
+        }
+    }
+}
+pub struct ReentrantMutexGuard<'a, T: 'a> {
+    mutex: &'a ReentrantMutex<T>,
+    content: &'a T,
+}
+impl<'a, T> Deref for MutexGuard {
+}