SI-8788 Add generic signature to Parcelable static field special case.

Android's AIDL generates Java code that assumes the presence of generic
annotations for Parcelable classes, which previously were not being
generated. This patch adds a generic signature to the generated CREATOR
field, resolving the issue.

Same as https://github.com/scala/scala/pull/3922 except into 2.11.x instead of 2.12.x.
I think for modules this is not correct, if you have

```
object T extends android.os.Parcelable { }
```

then the signature should be `android/os/Parcelable$Creator<T$;>;`, i.e., pass the module class `T$` instead of just `T`. Also, believe it or not, there are 4 places in the 2 backends where the signature needs to be added.

Also, as @soc noted, the duplicated `android.os.Parcelable.android.os.Parcelable$Creator` (see check file) seems wrong.

I will take over this change, do a cleanup refactoring in the backend, and also add the correct signature. I close this PR for now.