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

fusl/src/time/clock_nanosleep.c

Index: fusl/src/time/clock_nanosleep.c
diff --git a/fusl/src/time/clock_nanosleep.c b/fusl/src/time/clock_nanosleep.c
new file mode 100644
index 0000000000000000000000000000000000000000..ec87b9e33252c8f0a1cb9f04794c2365354f74db
--- /dev/null
+++ b/fusl/src/time/clock_nanosleep.c
@@ -0,0 +1,8 @@
+#include <time.h>
+#include "syscall.h"
+#include "libc.h"
+
+int clock_nanosleep(clockid_t clk, int flags, const struct timespec *req, struct timespec *rem)
+{
+	return -__syscall_cp(SYS_clock_nanosleep, clk, flags, req, rem);
+}