Linting: improve variable scoping

Linting: improve variable scoping

Declare variables at their first site of use where possible, especially
those with the cleanup attribute, but also some arrays that have to be
zeroed before use. This way we won't have wasted time preparing them if
an earlier step fails.

Change-Id: Ic46bdd38915f709bac37c7bfff9ba6dcb19f7657