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

fusl/src/thread/pthread_self.c

Index: fusl/src/thread/pthread_self.c
diff --git a/fusl/src/thread/pthread_self.c b/fusl/src/thread/pthread_self.c
new file mode 100644
index 0000000000000000000000000000000000000000..241a6202d2ea5e15ca53a5e8676398f6c5c95b8e
--- /dev/null
+++ b/fusl/src/thread/pthread_self.c
@@ -0,0 +1,11 @@
+#include "pthread_impl.h"
+#include <threads.h>
+#include "libc.h"
+
+static pthread_t __pthread_self_internal()
+{
+	return __pthread_self();
+}
+
+weak_alias(__pthread_self_internal, pthread_self);
+weak_alias(__pthread_self_internal, thrd_current);