pgsql: Refactor PinBufferForBlock() to remove checks about persistence.

Refactor PinBufferForBlock() to remove checks about persistence.

There are checks in PinBufferForBlock() function to set persistence of
the relation.  This function is called for each block in the relation.
Instead, set persistence of the relation before PinBufferForBlock().

Nazir Bilal Yavuz

Discussion: https://postgr.es/m/CAN55FZ0JKL6vk1xQp6rfOXiNFV1u1H0tJDPPGHWoiO3ea2Wc=A@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/af07a827b9c579be64f144f88e03bff3bb85582c

Modified Files
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src/backend/storage/aio/read_stream.c |  2 +-
src/backend/storage/buffer/bufmgr.c   | 27 +++++++++++++++------------
src/include/storage/bufmgr.h          |  2 +-
3 files changed, 17 insertions(+), 14 deletions(-)