On armv6 and later, use the WriteNotRead bit of the fault status register
to decide what protections are required by the faulting access.  The old
code disassembled the faulting instruction, and there are a lot of new
instructions that aren't handled.  The old code is still used for armv4/5
which doesn't have the WNR bit)
Provide additional information in some panic strings.

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