pgsql: Fix more format truncation issues

Fix more format truncation issues

Fix the warnings created by the compiler warning options
-Wformat-overflow=2 -Wformat-truncation=2, supported since GCC 7.  This
is a more aggressive variant of the fixes in
6275f5d28a1577563f53f2171689d4f890a46881, which GCC 7 warned about by
default.

The issues are all harmless, but some dubious coding patterns are
cleaned up.

One issue that is of external interest is that BGW_MAXLEN is increased
from 64 to 96.  Apparently, the old value would cause the bgw_name of
logical replication workers to be truncated in some circumstances.

But this doesn't actually add those warning options.  It appears that
the warnings depend a bit on compilation and optimization options, so it
would be annoying to have to keep up with that.  This is more of a
once-in-a-while cleanup.

Reviewed-by: Michael Paquier <michael@paquier.xyz>

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/3a4b891964a531aa7d242a48fcd9e41379863ead

Modified Files
--------------
contrib/pgstattuple/pgstattuple.c        |  2 +-
src/backend/commands/explain.c           |  5 +++--
src/backend/libpq/be-secure-openssl.c    |  2 +-
src/backend/utils/adt/dbsize.c           |  2 +-
src/backend/utils/adt/float.c            | 24 ++++++++++-------------
src/backend/utils/adt/formatting.c       | 33 ++++++++++----------------------
src/backend/utils/misc/guc.c             |  4 ++--
src/bin/initdb/initdb.c                  |  6 +++---
src/bin/pg_dump/pg_backup_archiver.c     |  2 +-
src/bin/pg_dump/pg_backup_tar.c          |  2 +-
src/bin/pgbench/pgbench.c                |  4 ++--
src/include/postmaster/bgworker.h        |  2 +-
src/interfaces/libpq/fe-secure-openssl.c |  2 +-
src/pl/tcl/pltcl.c                       |  2 +-
14 files changed, 38 insertions(+), 54 deletions(-)