pgsql: Fix misleading comment in nodeIndexonlyscan.c.

Fix misleading comment in nodeIndexonlyscan.c.

The stated reason for acquiring predicate locks on heap pages hasn't
existed since commit c01262a8, so fix the comment.  Perhaps in a later
release we'll also be able to change the code to use tuple locks.

Back-patch all the way.

Reviewed-by: Ashwin Agrawal
Discussion: https://postgr.es/m/CAEepm%3D2GK3FVdnt5V3d%2Bh9njWipCv_fNL%3DwjxyUhzsF%3D0PcbNg%40mail.gmail.com

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/69da8c1e69efd3a5b1b0f1d9bd8b7b79a696fbc8

Modified Files
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src/backend/executor/nodeIndexonlyscan.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)