Properly end minidump filename with a NULL byte
Properly end minidump filename with a NULL byte

[Fixes #11494]

(cherry picked from commit d5b459e162387b65d73fcc17b8a2a17e417b797b)

greenplum-db/gporca,greenplum-db/gporca,greenplum-db/gporca,greenplum-db/gporca