pgsql: Avoid spurious Hot Standby conflicts from btree delete records.

Avoid spurious Hot Standby conflicts from btree delete records.
Similar conflicts were already avoided for related record types.
Massive over-caution resulted in a usability bug. Clear theoretical
basis for doing this is now confirmed by me.
Request to remove from Heikki (twice), over-caution by me.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=52010027efc8757fdd830a4d0113763a501259bc

Modified Files
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src/backend/storage/ipc/standby.c |   18 +++++-------------
1 files changed, 5 insertions(+), 13 deletions(-)