pgsql: Fix confusion about data type of pg_class.relpages and relallvis

Fix confusion about data type of pg_class.relpages and relallvisible.

Although they're exposed as int4 in pg_class, relpages and
relallvisible are really of type BlockNumber, that is uint32.
Correct type puns in relation_statistics_update() and remove
inappropriate range-checks. The type puns are only cosmetic
issues, but the range checks would cause failures with huge
relations.

Reported-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Author: Corey Huinker <corey(dot)huinker(at)gmail(dot)com>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/614341.1740269035@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9de2cc455eb9c60dda979c32985df967522a8ab2

Modified Files
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src/backend/statistics/relation_stats.c | 53 ++++++++-------------------------
1 file changed, 13 insertions(+), 40 deletions(-)