pgsql: bufmgr: Make definitions related to buffer descriptor easier to

bufmgr: Make definitions related to buffer descriptor easier to modify

This is in preparation to widening the buffer state to 64 bits, which in turn
is preparation for implementing content locks in bufmgr. This commit aims to
make the subsequent commits a bit easier to review, by separating out
reformatting etc from the actual changes.

Reviewed-by: Melanie Plageman <melanieplageman(at)gmail(dot)com>
Discussion: https://postgr.es/m/4csodkvvfbfloxxjlkgsnl2lgfv2mtzdl7phqzd4jxjadxm4o5@usw7feyb5bzf

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ff219c19878960d6af3fb8e08789018745f91895

Modified Files
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src/include/storage/buf_internals.h | 65 +++++++++++++++++++++++++++----------
1 file changed, 47 insertions(+), 18 deletions(-)