Remove useless initializations
The struct is already initialized to all zeros right before this, and
randomly initializing a few but not all fields to zero again has no
technical or educational value.
Reviewed-by: Tomasz Rybak <tomasz.rybak@post.pl>
Discussion: https://www.postgresql.org/message-id/flat/
a368248e-69e4-40be-9c07-
6c3b5880b0a6@eisentraut.org