RFR 8191278: MappedByteBuffer bulk access memory failures are not handled gracefully

[Nick Gasson]

Hi Jamsheed,

On 10/04/2019 02:13, Jamsheed wrote:
> 
> i could reproduce the sigsegv. was using slowdebug bits today morning, 
> and so it didn't fail.
> 

Does the segfault only happen on release builds? I tried webrev.04 again 
on an AArch64 system with release, fastdebug, and slowdebug but I still 
don't see this crash :-/.

Nick