vendor: update buildkit to 8effd45b

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/gopkg.in/yaml.v2/yaml.go

@@ -175,7 +175,7 @@ func unmarshal(in []byte, out interface{}, strict bool) (err error) {
 //                  Zero valued structs will be omitted if all their public
 //                  fields are zero, unless they implement an IsZero
 //                  method (see the IsZeroer interface type), in which
-//                  case the field will be included if that method returns true.
+//                  case the field will be excluded if IsZero returns true.
 //
 //     flow         Marshal using a flow style (useful for structs,
 //                  sequences and maps).
@@ -464,3 +464,15 @@ func isZero(v reflect.Value) bool {
 	}
 	return false
 }
+
+// FutureLineWrap globally disables line wrapping when encoding long strings.
+// This is a temporary and thus deprecated method introduced to faciliate
+// migration towards v3, which offers more control of line lengths on
+// individual encodings, and has a default matching the behavior introduced
+// by this function.
+//
+// The default formatting of v2 was erroneously changed in v2.3.0 and reverted
+// in v2.4.0, at which point this function was introduced to help migration.
+func FutureLineWrap() {
+	disableLineWrapping = true
+}