[v5 07/20] x86/insn-eval: Add utility function to get segment descriptor

The segment descriptor contains information that is relevant to how linear address need to be computed. It contains the default size of addresses as well as the base address of the segment. Thus, given a segment selector, we ought look at segment descriptor to correctly calculate the linear

[v5 07/20] x86/insn-eval: Add utility function to get segment descriptor

The segment descriptor contains information that is relevant to how linear address need to be computed. It contains the default size of addresses as well as the base address of the segment. Thus, given a segment selector, we ought look at segment descriptor to correctly calculate the linear