pgsql: Change stat_lock.wait_time to double precision

Change stat_lock.wait_time to double precision

Other statistics views (pg_stat_io, pg_stat_database, etc.) use float8
for all measured-time columns, the new pg_stat_lock standing out as an
outlier by using bigint.

This commit aligns pg_stat_lock with the other stats views for
consistency. Like pg_stat_io, the time is stored in microseconds, and
is displayed in milliseconds with a conversion done when the view is
queried.

While on it, replace a use of "long" by PgStat_Counter, the former could
overflow for large wait times where sizeof(long) is 4 bytes (aka WIN32).

Bump catalog version.

Author: Tatsuya Kawata <kawatatatsuya0913(at)gmail(dot)com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Discussion: https://postgr.es/m/CAHza6qerEiQehrbW5xaXyxvR0qJe3KBX1R4kocDz1+7Ygu8x-g@mail.gmail.com
Backpatch-through: 19

Branch
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REL_19_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/ff6f6e0470ecb362a389bb20aac46a843e496c2f

Modified Files
--------------
doc/src/sgml/monitoring.sgml | 2 +-
src/backend/storage/lmgr/proc.c | 9 +++++----
src/backend/utils/activity/pgstat_lock.c | 4 ++--
src/backend/utils/adt/pgstatfuncs.c | 2 +-
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 2 +-
src/include/pgstat.h | 5 +++--
7 files changed, 14 insertions(+), 12 deletions(-)