[foreign-memaccess] RFR 8234581: Cleanup use of exceptions in the memory access API

[Maurizio Cimadamore]

New day, new cleanup :-)

This time, following some of the indications from Paul, the goal is to 
cleanup usages of exceptions in the memory access API. I found 4 broad 
categories of issues:

- We sometimes throw IAE where an IOOB would be preferred (namely, 
MemorySegment::slice and MemoryAddress::copy)

- We sometimes use RuntimeException to document unforeseen failures of 
Unsafe::allocateMemory (ByteBuffer::allocateDirect does not do so)

- The handling of exceptions when forming layout paths is plain 
inconsistent - and IAE should be used throughout

- MemorySegment::close should always throw ISE if the state is not valid


The changes in LayoutPath handling required some deeper changes in the 
implementation - which now triggers an uniform IAE with a message of the 
kind: Bad layout path: <cause>.


Since I was there, I also added the logic to zero the native memory 
allocated with MemorySegment::allocateNative. This behavior can be 
disabled with a runtime flag: -Djdk.internal.foreign.skipZeroMemory.


I also made extra sure that the exceptions thrown in the code are 
reflected in the throws clause of the API methods, and that there are 
the right @throw taglets for them.

Webrev:

http://cr.openjdk.java.net/~mcimadamore/panama/8234581/

javadoc:

cr.openjdk.java.net/~mcimadamore/panama/8234581_javadoc


Cheers
Maurizio