XLOG_PARAMETER_CHANGE handling of wal_log_hints

Hi,

when I was fixing how commit_ts handles the XLOG_PARAMETER_CHANGE I
noticed that for wal_log_hints we assign the value in ControFile to
current value instead of value that comes from WAL.

ISTM it has just information value so it should not have any practical
impact, but it looks like a bug anyway so here is simple patch to change
that.

--
  Petr Jelinek                  http://www.2ndQuadrant.com/
  PostgreSQL Development, 24x7 Support, Training & Services