Add unconverted reason for jarjar incompatibility.

Test: m bp2build
Change-Id: I112b84fa53f57b9df2bd1e1616012fe55b48001e

java/app.go

@@ -1613,7 +1613,10 @@ type bazelAndroidAppAttributes struct {
 
 // ConvertWithBp2build is used to convert android_app to Bazel.
 func (a *AndroidApp) ConvertWithBp2build(ctx android.TopDownMutatorContext) {
-	commonAttrs, bp2BuildInfo := a.convertLibraryAttrsBp2Build(ctx)
+	commonAttrs, bp2BuildInfo, supported := a.convertLibraryAttrsBp2Build(ctx)
+	if !supported {
+		return
+	}
 	depLabels := bp2BuildInfo.DepLabels
 
 	deps := depLabels.Deps