Function: hack-local-variables-confirm

Get confirmation before setting up local variable values.
ALL-VARS is the list of all variables to be set up.
UNSAFE-VARS is the list of those that aren't marked as safe or risky.
RISKY-VARS is the list of those that are marked as risky.
If these settings come from directory-local variables, then
DIR-NAME is the name of the associated directory. Otherwise it is nil.