Fix pgstat_count_io_op_time() calls passing incorrect information

Fix pgstat_count_io_op_time() calls passing incorrect information

Several calls of pgstat_count_io_op_time() have been used as data to
count negative values returned by pg_pread() or pg_pwrite(), leading to
an incorrect count reported, casting them back to uint64.

Most of the problematic calls updated here are adjusted so as we do not
report buggy negative numbers anymore.  In xlogrecovery.c, the spot
updated still counts short reads.  In xlog.c, after a WAL segment
initialization, I/O numbers are aggregated only after checking that the
operation has succeeded.

issues introduced by a051e71e28a1.

Reported-by: Peter Eisentraut <peter@eisentraut.org>
Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Discussion: https://postgr.es/m/0db864e6-4477-4eba-b2be-d3523cc86564@eisentraut.org
Backpatch-through: 18