Follow ExecOpenIndices API changes for PostgreSQL 9.5.
Follow ExecOpenIndices API changes for PostgreSQL 9.5.

By commit [168d58] of PostgreSQL, ExecOpenIndices has
gotten one more argument, bool speculative. This can
be used for INSERT...ON CONFLICT and seems to be not
related to bulkload.

ooyamams/pg_bulkload,ooyamams/pg_bulkload,ooyamams/pg_bulkload