getAndAddInt() breaks AOT compilation for AArch64

[Andrew Haley]

The problem is that the new code assumes that the delta is passed
in a register, but the caller does not allocate a register for it.

In AArch64AtomicMove.java, delta must be an AllocatableValue, and the
caller at AArch64LIRGenerator.java must call asAllocatable(delta).

An alternative might be to special-case integer values that will fit
in an immediate operand and generate an immediate add.  But, please do
something: AOT is broken until you patch it.  Thank you.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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