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

fusl/src/linux/adjtime.c

Index: fusl/src/linux/adjtime.c
diff --git a/fusl/src/linux/adjtime.c b/fusl/src/linux/adjtime.c
new file mode 100644
index 0000000000000000000000000000000000000000..fa8af9f021773f575989fb34b872699434cfe4cf
--- /dev/null
+++ b/fusl/src/linux/adjtime.c
@@ -0,0 +1,27 @@
+#define _GNU_SOURCE
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <errno.h>
+#include "syscall.h"
+
+int adjtime(const struct timeval *in, struct timeval *out)
+{
+	struct timex tx = { 0 };
+	if (in) {
+		if (in->tv_sec > 1000 || in->tv_usec > 1000000000) {
+			errno = EINVAL;
+			return -1;
+		}
+		tx.offset = in->tv_sec*1000000 + in->tv_usec;
+		tx.modes = ADJ_OFFSET_SINGLESHOT;
+	}
+	if (syscall(SYS_adjtimex, &tx) < 0) return -1;
+	if (out) {
+		out->tv_sec = tx.offset / 1000000;
+		if ((out->tv_usec = tx.offset % 1000000) < 0) {
+			out->tv_sec--;
+			out->tv_usec += 1000000;
+		}
+	}
+	return 0;
+}