gdatainputstream: Deprecate read_until() in favour of read_upto()

g_data_input_stream_read_upto() was introduced in 2.26; now it’s GLib
2.56, we can probably deprecate the old versions (since the handling of
consuming the stop character differs between the sync and async versions
of it).

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://bugzilla.gnome.org/show_bug.cgi?id=584284

gio/tests/data-input-stream.c

@@ -222,6 +222,8 @@ test_read_lines_LF_invalid_utf8 (void)
   g_object_unref (stream);
 }
 
+G_GNUC_BEGIN_IGNORE_DEPRECATIONS
+
 static void
 test_read_until (void)
 {
@@ -268,6 +270,8 @@ test_read_until (void)
   g_object_unref (stream);
 }
 
+G_GNUC_END_IGNORE_DEPRECATIONS
+
 static void
 test_read_upto (void)
 {