pgsql: pgstat: normalize function naming.

pgstat: normalize function naming.

Most of pgstat uses pgstat_<verb>_<subject>() or just <verb>_<subject>(). But
not all (some introduced fairly recently by me). Rename ones that aren't
intentionally following a different scheme (e.g. AtEOXact_*).

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/be902e26510788c70a874ea54bad753b723d018f

Modified Files
--------------
src/backend/access/common/relation.c         |  4 +--
src/backend/access/transam/slru.c            |  2 +-
src/backend/postmaster/pgstat.c              |  4 +--
src/backend/utils/activity/pgstat_relation.c | 38 ++++++++++++++--------------
src/backend/utils/activity/pgstat_slru.c     | 24 +++++++++---------
src/backend/utils/activity/pgstat_wal.c      |  4 +--
src/backend/utils/activity/pgstat_xact.c     |  6 ++---
src/backend/utils/adt/pgstatfuncs.c          |  2 +-
src/include/pgstat.h                         | 22 ++++++++--------
src/include/utils/pgstat_internal.h          |  7 +++--
10 files changed, 56 insertions(+), 57 deletions(-)