gdb/dwarf: rename cooked_index::m_vector to m_shards

I think that is clearer and helps readability.

Rename a few iteration variables from "index" or "idx" to "shard".  In
my mental model, the "index" is the whole thing, so it's confusing to
use that word when referring to shards.

Change-Id: I208cb839e873c514d1f8eae250d4a16f31016148
Approved-By: Tom Tromey <tom@tromey.com>
2 files changed