encoding/openapi: rewrite uses of deprecated cue.Value methods

cue.Value.Reference can be rewritten with cue.Value.ReferencePath,
and cue.Value.Elem can be rewritten with cue.Value.LookupPath
with either cue.AnyString or cue.AnyIndex, depending on whether
the value is a struct or a list.

Signed-off-by: Daniel Martí <[e-mail]>
Change-Id: I092707aafe89feb4dbf3e7fd9980f0deb73940a4
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1206354
Unity-Result: CUE porcuepine <[e-mail]>
Reviewed-by: Paul Jolly <[e-mail]>
TryBot-Result: CUEcueckoo <[e-mail]>

encoding/openapi/build.go

···
 			default:
 				a := appendSplit(nil, cue.OrOp, v)
 				for i, v := range a {
-					if _, r := v.Reference(); len(r) == 0 {
+					if _, r := v.ReferencePath(); len(r.Selectors()) == 0 {
 						a[i] = v.Eval()
 					}
 				}
···
 		b.setSingle("properties", (*ast.StructLit)(properties), false)
 	}
 
-	if t, ok := v.Elem(); ok &&
+	if t := v.LookupPath(cue.MakePath(cue.AnyString)); t.Exists() &&
 		(b.core == nil || b.core.items == nil) && b.checkCycle(t) {
 		schema := b.schema(nil, cue.AnyString, t)
 		if len(schema.Elts) > 0 {
···
 	}
 
 	if !hasMax || int64(len(items)) < maxLength {
-		if typ, ok := v.Elem(); ok && b.checkCycle(typ) {
+		if typ := v.LookupPath(cue.MakePath(cue.AnyIndex)); typ.Exists() && b.checkCycle(typ) {
 			var core *builder
 			if b.core != nil {
 				core = b.core.items

encoding/openapi/crd.go

···
 	defer b.popNode()
 
 	if !b.ctx.expandRefs {
-		_, r := v.Reference()
-		if len(r) > 0 {
+		_, r := v.ReferencePath()
+		if len(r.Selectors()) > 0 {
 			return
 		}
 	}
···
 
 		switch b.kind {
 		case cue.StructKind:
-			if typ, ok := v.Elem(); ok {
+			if typ := v.LookupPath(cue.MakePath(cue.AnyString)); typ.Exists() {
 				if !b.checkCycle(typ) {
 					return
 				}
···
 			b.buildCoreStruct(v)
 
 		case cue.ListKind:
-			if typ, ok := v.Elem(); ok {
+			if typ := v.LookupPath(cue.MakePath(cue.AnyIndex)); typ.Exists() {
 				if !b.checkCycle(typ) {
 					return
 				}