Since parcelize is Android specific, it should only be enabled for
Android compilation. In order to allow parcelize to generate code
for declarations in common code, we make checkers platform checkers
and we allow the registration of an additional annotations to
trigger parcelize processing.
That way, code such as:
```
package my.package
annotation class Parcelize
expect interface MyParcelable
@Parcelize
data class User(name: String): MyParcelable
```
Will work with an Android platform actual of the form:
```
actual typealias MyParcelable = android.os.Parcelable
```
And telling the plugin to trigger parcelize processing with the
additional annotation `my.package.Parcelize`.
Fixes https://issuetracker.google.com/315775835.
There's no way for the end user to use this implementation anymore,
since old JVM backend cannot be enabled, and nothing else from Kotlin
depends on it.
Mads Ager