x86: pull CL18840 - SDM->x86.csv converter

Add x86spec package that is capable to generate x86.csv
version 0.2.

New x86.csv does not replace v0.1 to avoid unexpected
code breaks (x86/x86map depends on v0.1).
This can be solved in another CL.

The rationale behind this is x86avxgen tool that
requires v0.2 spec.

See https://go-review.googlesource.com/#/c/arch/+/18840/

Change-Id: Iea93e1174a5a79b9b50bf99f626e3c48b19ad5c1
Reviewed-on: https://go-review.googlesource.com/66970
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
7 files changed