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

fusl/include/sys/timerfd.h

Index: fusl/include/sys/timerfd.h
diff --git a/fusl/include/sys/timerfd.h b/fusl/include/sys/timerfd.h
new file mode 100644
index 0000000000000000000000000000000000000000..9724d903472c52b5ec4528604816c9601047e317
--- /dev/null
+++ b/fusl/include/sys/timerfd.h
@@ -0,0 +1,26 @@
+#ifndef _SYS_TIMERFD_H
+#define _SYS_TIMERFD_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <time.h>
+#include <fcntl.h>
+
+#define TFD_NONBLOCK O_NONBLOCK
+#define TFD_CLOEXEC O_CLOEXEC
+
+#define TFD_TIMER_ABSTIME 1
+
+struct itimerspec;
+
+int timerfd_create(int, int);
+int timerfd_settime(int, int, const struct itimerspec *, struct itimerspec *);
+int timerfd_gettime(int, struct itimerspec *);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif