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

fusl/src/unistd/ualarm.c

Index: fusl/src/unistd/ualarm.c
diff --git a/fusl/src/unistd/ualarm.c b/fusl/src/unistd/ualarm.c
new file mode 100644
index 0000000000000000000000000000000000000000..855504bca42c743580fbbb3425a3176736411c7a
--- /dev/null
+++ b/fusl/src/unistd/ualarm.c
@@ -0,0 +1,13 @@
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/time.h>
+
+unsigned ualarm(unsigned value, unsigned interval)
+{
+	struct itimerval it = {
+		.it_interval.tv_usec = interval,
+		.it_value.tv_usec = value
+	};
+	setitimer(ITIMER_REAL, &it, &it);
+	return it.it_value.tv_sec*1000000 + it.it_value.tv_usec;
+}