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

fusl/src/unistd/alarm.c

Index: fusl/src/unistd/alarm.c
diff --git a/fusl/src/unistd/alarm.c b/fusl/src/unistd/alarm.c
new file mode 100644
index 0000000000000000000000000000000000000000..2e3263ac5986019f57576f6b0777f483b449eba7
--- /dev/null
+++ b/fusl/src/unistd/alarm.c
@@ -0,0 +1,10 @@
+#include <unistd.h>
+#include <sys/time.h>
+#include "syscall.h"
+
+unsigned alarm(unsigned seconds)
+{
+	struct itimerval it = { .it_value.tv_sec = seconds };
+	__syscall(SYS_setitimer, ITIMER_REAL, &it, &it);
+	return it.it_value.tv_sec + !!it.it_value.tv_usec;
+}