ARITHMETIC-ERROR-OPERANDS, -OPERATION not set to meaningful values on x86, ARM

[gb]

When a SIGFPE (or equivalent) is received, we need to try harder to determine the operation/operands to fully initialize the resulting ARITHMETIC-ERROR condition.

On x86, CCL::DECODE-ARITHMETIC-ERROR doesn't try very hard. On ARM, nothing tries at all (though we don't actually get a SIGFPE.)

The PPC ports disassembled the instruction that caused the exception; the other ports need to do the same thing.

[gb]

This should be fixed (at the very least, much improved) in the trunk as of roughly r14842. (There've been a series of platform-specific commits, some related to this tickt and some not too related ...)