Testing assistance requested: ARM/PPC/S390 and a little Aarch64

[David Holmes]

Hi,

I was hoping some folk may be able to take this preliminary patch for a 
spin for me as I don't have access to a full range of hardware:

http://cr.openjdk.java.net/~dholmes/8234372/webrev/

The patch relates to:

https://bugs.openjdk.java.net/browse/JDK-8234372

'Investigate use of Thread::stack_base() and queries for "in stack"'

The main functional changes here are in frame::safe_for_sender where we 
bring ARM/PPC/S390/Sparc into line with x86 and Aarch64 with regards to 
incorrect uses of >= or <= when comparing values with Thread::stack_base().

In addition this standardises the main sp safety check to reuse 
Thread::is_in_usable_stack().

And finally (with regards to the testing request) it fixes the validity 
check for "locals" wrt. Thread::stack_base().

Thanks,
David