implement SuSv3 required ualarm()

libc/unistd/ualarm.c

@@ -0,0 +1,19 @@
+#define _GNU_SOURCE
+#include <time.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+useconds_t ualarm(useconds_t value, useconds_t interval)
+{
+    struct itimerval otimer;
+    const struct itimerval itimer = {
+	{ 0, interval },
+	{ 0, value}
+    };
+
+    if (setitimer(ITIMER_REAL, &itimer, &otimer) < 0) {
+	return -1;
+    }
+    return((otimer.it_value.tv_sec * 1000000) + otimer.it_value.tv_usec);
+}