[vala/staging] gstreamer: Update from 1.17.0+ git master

[Rico Tzschichholz <ricotz src gnome org>]

commit b23471650480d8964c2b35aa84159cf46fed3a11
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Nov 27 13:57:21 2019 +0100

    gstreamer: Update from 1.17.0+ git master

 vapi/gstreamer-1.0.vapi | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/vapi/gstreamer-1.0.vapi b/vapi/gstreamer-1.0.vapi
index 88811ee60..b3a3b1389 100644
--- a/vapi/gstreamer-1.0.vapi
+++ b/vapi/gstreamer-1.0.vapi
@@ -1056,7 +1056,13 @@ namespace Gst {
                [CCode (has_construct_function = false)]
                public DateTime.from_unix_epoch_local_time (int64 secs);
                [CCode (has_construct_function = false)]
+               [Version (since = "1.18")]
+               public DateTime.from_unix_epoch_local_time_usecs (int64 usecs);
+               [CCode (has_construct_function = false)]
                public DateTime.from_unix_epoch_utc (int64 secs);
+               [CCode (has_construct_function = false)]
+               [Version (since = "1.18")]
+               public DateTime.from_unix_epoch_utc_usecs (int64 usecs);
                public int get_day ();
                public int get_hour ();
                public int get_microsecond ();