pgsql: Add vacuum_delay_point call in compute_index_stats's per-sample-

Add vacuum_delay_point call in compute_index_stats's per-sample-row loop.

Slow functions in index expressions might cause this loop to take long
enough to make it worth being cancellable.  Probably it would be enough
to call CHECK_FOR_INTERRUPTS here, but for consistency with other
per-sample-row loops in this file, let's use vacuum_delay_point.

Report and patch by Jeff Janes.  Back-patch to all supported branches.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/e4cbfd673d530a3e841db26a74f22e11a991205a

Modified Files
--------------
src/backend/commands/analyze.c |    2 ++
1 file changed, 2 insertions(+)