[Trivial] Do not shadow members in dbwrapper #8467

This is a followup to #8105.

dbwrapper.h code shadows some members. Fixes use underscore prefix (I also migrated piterIn into _piter to follow this style).

For review, compare binaries or compile with -Wshadow and compare complete logs.

Is there an advantage to create multiple pulls for this? If the review is mechanic, it would help to have as few as possible.

I'm trying to group similar changes. Reviewing 42 changed files at once is not easy and it is very time consuming to do it right. I prefer tackling the task in steps/groups.

This particular change group of one file only unfortunately.

ut ACK

utACK 4a35e0f (Gives same binaries)

utACK 4a35e0f34c0d1c2bbcae6d7b6d691fb0df946dfe