Endianness: Make it easier to check the compiled in guest endianness.
Endianness: Make it easier to check the compiled in guest endianness.

It was technically possible but clumsy to determine what endianness a guest
was configured with using the state in byteswap.hh. This change makes that
information available more directly.

Also get rid of unused (and mildly redundant) ByteOrderDiffers constant.

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin