[fuchsia] Migrate to zx_clock_get_new

This CL prepares for changing the zx_clock_get signature.

Change-Id: I8fd21d61c7c05b40cca0561def274793780d3ace
diff --git a/src/runtime/os_fuchsia.go b/src/runtime/os_fuchsia.go
index 4cf764e..bc5be88 100644
--- a/src/runtime/os_fuchsia.go
+++ b/src/runtime/os_fuchsia.go
@@ -248,14 +248,15 @@
 
 //go:nosplit
 func nanotime() int64 {
-	return int64(zx.Sys_clock_get(ZX_CLOCK_MONOTONIC))
+	return int64(zx.Sys_clock_get_monotonic())
 }
 
 //go:linkname time_now time.now
 //go:nosplit
 func time_now() (sec int64, nsec int32, mono int64) {
 	const ZX_CLOCK_UTC = 1
-	x := int64(zx.Sys_clock_get(ZX_CLOCK_UTC))
+	var x zx.Time
+	zx.Sys_clock_get_new(ZX_CLOCK_UTC, &x)
 	return int64(x / 1e9), int32(x % 1e9), nanotime()
 }