x86: Fix moffset decoding

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: Fix OP_MEM disasm

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: Fix disasm hexadecimal prints

Makes the output look more similar to objdump which simplifies
debugging...

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: moffset size depends on address-size

It's sometimes helpful to RTFM:

  The moffs8, moffs16, moffs32 and moffs64 operands specify a simple
  offset relative to the segment base, where 8, 16, 32 and 64 refer to
  the size of the data. The address-size attribute of the instruction
  determines the size of the offset, either 16, 32 or 64 bits.

We are emulating 8086 so address-size is always 16 bits.

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: Opcode 75 is JNE, not JNZ

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: Fix read_s8() signedness issue...

Signed-off-by: Pekka Enberg <penberg@iki.fi>
x86: Fix decode_rel to use rel_data

Signed-off-by: Pekka Enberg <penberg@iki.fi>