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

fusl/src/thread/cnd_wait.c

Index: fusl/src/thread/cnd_wait.c
diff --git a/fusl/src/thread/cnd_wait.c b/fusl/src/thread/cnd_wait.c
new file mode 100644
index 0000000000000000000000000000000000000000..602796f85b5c3c801208c34b0733377e22240173
--- /dev/null
+++ b/fusl/src/thread/cnd_wait.c
@@ -0,0 +1,9 @@
+#include <threads.h>
+
+int cnd_wait(cnd_t *c, mtx_t *m)
+{
+	/* Calling cnd_timedwait with a null pointer is an extension.
+	 * It is convenient here to avoid duplication of the logic
+	 * for return values. */
+	return cnd_timedwait(c, m, 0);
+}