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

fusl/src/internal/futex.h

Index: fusl/src/internal/futex.h
diff --git a/fusl/src/internal/futex.h b/fusl/src/internal/futex.h
new file mode 100644
index 0000000000000000000000000000000000000000..cf4c79513e240777b2a2335e604e41814206db26
--- /dev/null
+++ b/fusl/src/internal/futex.h
@@ -0,0 +1,21 @@
+#ifndef _INTERNAL_FUTEX_H
+#define _INTERNAL_FUTEX_H
+
+#define FUTEX_WAIT		0
+#define FUTEX_WAKE		1
+#define FUTEX_FD		2
+#define FUTEX_REQUEUE		3
+#define FUTEX_CMP_REQUEUE	4
+#define FUTEX_WAKE_OP		5
+#define FUTEX_LOCK_PI		6
+#define FUTEX_UNLOCK_PI		7
+#define FUTEX_TRYLOCK_PI	8
+#define FUTEX_WAIT_BITSET	9
+
+#define FUTEX_PRIVATE 128
+
+#define FUTEX_CLOCK_REALTIME 256
+
+int __futex(volatile int *, int, int, void *);
+
+#endif