RFR: 8365558: Fix stub entry init and blob creation on Zero [v3]

[Vladimir Kozlov]

On Fri, 15 Aug 2025 15:21:26 GMT, Andrew Dinn <adinn at openjdk.org> wrote:

>> Fix two problems with Zero blob/stub entry initialization:
>> 1. Stop Zero allocating AdapterBlobs for the default set of i2c2i adapters even though it cannot ever use them.
>> 2. Allow Zero to execute its stubgen init functions even though it is not generating code into a code buffer (i.e when blob size is declared as zero). This still allows it initialize entries to point to C functions. n.b. this was broken when [JDK-8359373](https://bugs.openjdk.org/browse/JDK-8359373) introduced the preuniverse Stubgen stub group.
>
> Andrew Dinn has updated the pull request incrementally with one additional commit since the last revision:
> 
>   relocate  return to correct scope

My testing passed. Good.

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PR Comment: https://git.openjdk.org/jdk/pull/26787#issuecomment-3192813956