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

fusl/src/time/clock_gettime.c

Index: fusl/src/time/clock_gettime.c
diff --git a/fusl/src/time/clock_gettime.c b/fusl/src/time/clock_gettime.c
new file mode 100644
index 0000000000000000000000000000000000000000..1572de0ef0029eb94b53a9928cd0a9fc57684d6a
--- /dev/null
+++ b/fusl/src/time/clock_gettime.c
@@ -0,0 +1,41 @@
+#include <time.h>
+#include <errno.h>
+#include <stdint.h>
+#include "syscall.h"
+#include "libc.h"
+#include "atomic.h"
+
+static int sc_clock_gettime(clockid_t clk, struct timespec *ts)
+{
+	int r = __syscall(SYS_clock_gettime, clk, ts);
+	if (!r) return r;
+	if (r == -ENOSYS) {
+		if (clk == CLOCK_REALTIME) {
+			__syscall(SYS_gettimeofday, ts, 0);
+			ts->tv_nsec = (int)ts->tv_nsec * 1000;
+			return 0;
+		}
+		r = -EINVAL;
+	}
+	errno = -r;
+	return -1;
+}
+
+void *__vdsosym(const char *, const char *);
+
+int __clock_gettime(clockid_t clk, struct timespec *ts)
+{
+#ifdef VDSO_CGT_SYM
+	static int (*volatile cgt)(clockid_t, struct timespec *);
+	if (!cgt) {
+		void *f = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
+		if (!f) f = (void *)sc_clock_gettime;
+		a_cas_p(&cgt, 0, f);
+	}
+	return cgt(clk, ts);
+#else
+	return sc_clock_gettime(clk, ts);
+#endif
+}
+
+weak_alias(__clock_gettime, clock_gettime);