Add a "fork" of musl as //fusl.

fusl/src/thread/pthread_mutex_timedlock.c

Index: fusl/src/thread/pthread_mutex_timedlock.c
diff --git a/fusl/src/thread/pthread_mutex_timedlock.c b/fusl/src/thread/pthread_mutex_timedlock.c
new file mode 100644
index 0000000000000000000000000000000000000000..0a240e7913418bd86a48c02977c6733e8e49c0f8
--- /dev/null
+++ b/fusl/src/thread/pthread_mutex_timedlock.c
@@ -0,0 +1,34 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
+{
+	if ((m->_m_type&15) == PTHREAD_MUTEX_NORMAL
+	    && !a_cas(&m->_m_lock, 0, EBUSY))
+		return 0;
+
+	int r, t, priv = (m->_m_type & 128) ^ 128;
+
+	r = pthread_mutex_trylock(m);
+	if (r != EBUSY) return r;
+	
+	int spins = 100;
+	while (spins-- && m->_m_lock && !m->_m_waiters) a_spin();
+
+	while ((r=pthread_mutex_trylock(m)) == EBUSY) {
+		if (!(r=m->_m_lock) || ((r&0x40000000) && (m->_m_type&4)))
+			continue;
+		if ((m->_m_type&3) == PTHREAD_MUTEX_ERRORCHECK
+		 && (r&0x7fffffff) == __pthread_self()->tid)
+			return EDEADLK;
+
+		a_inc(&m->_m_waiters);
+		t = r | 0x80000000;
+		a_cas(&m->_m_lock, r, t);
+		r = __timedwait(&m->_m_lock, t, CLOCK_REALTIME, at, priv);
+		a_dec(&m->_m_waiters);
+		if (r && r != EINTR) break;
+	}
+	return r;
+}
+
+weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);