RFR: 8271242: Add Arena regression tests

[Thomas Stuefe]

On Thu, 29 Jul 2021 21:39:48 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Looks good. Thank you for writing these tests.

Thank you Coleen!

> test/hotspot/gtest/memory/test_arena.cpp line 65:
> 
>> 63:   }
>> 64:   // Allocate again. The new allocations should have the same position as the 0-sized
>> 65:   // first one.
> 
> It seems so dangerous to allow zero sized Amalloc.

I agree, but I wanted these tests to test existing behavior.
I tried to do a quick "lets assert > 0" and that backfired, a bit of cleanup would be needed at the caller side.

-------------

PR: https://git.openjdk.java.net/jdk/pull/4909