pgsql: Remove redundant null pointer checks before free()

Remove redundant null pointer checks before free()

Per applicable standards, free() with a null pointer is a no-op.
Systems that don't observe that are ancient and no longer relevant.
Some PostgreSQL code already required this behavior, so this change
does not introduce any new requirements, just makes the code more
consistent.

Discussion: https://www.postgresql.org/message-id/flat/dac5d2d0-98f5-94d9-8e69-46da2413593d%40enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/02c408e21a6e78ff246ea7a1beb4669634fa9c4c

Modified Files
--------------
contrib/pg_stat_statements/pg_stat_statements.c | 12 +-
contrib/uuid-ossp/uuid-ossp.c | 6 +-
src/backend/bootstrap/bootstrap.c | 3 +-
src/backend/libpq/auth.c | 5 +-
src/backend/postmaster/postmaster.c | 3 +-
src/backend/regex/regc_pg_locale.c | 6 +-
src/backend/tcop/postgres.c | 3 +-
src/backend/utils/adt/pg_locale.c | 30 ++--
src/backend/utils/error/elog.c | 3 +-
src/backend/utils/init/miscinit.c | 3 +-
src/backend/utils/misc/guc.c | 24 +--
src/bin/pg_basebackup/pg_basebackup.c | 3 +-
src/bin/pg_basebackup/streamutil.c | 3 +-
src/bin/pg_dump/dumputils.c | 21 +--
src/bin/pg_dump/pg_backup_archiver.c | 60 +++----
src/bin/pg_dump/pg_backup_custom.c | 6 +-
src/bin/pg_dump/pg_backup_db.c | 3 +-
src/bin/pg_dump/pg_backup_tar.c | 3 +-
src/bin/pg_dump/pg_dump.c | 30 ++--
src/bin/pg_dump/pg_dumpall.c | 6 +-
src/bin/pgbench/pgbench.c | 6 +-
src/bin/psql/command.c | 66 +++-----
src/bin/psql/copy.c | 3 +-
src/bin/psql/describe.c | 6 +-
src/bin/psql/input.c | 3 +-
src/bin/psql/tab-complete.c | 15 +-
src/common/fe_memutils.c | 3 +-
src/fe_utils/connect_utils.c | 3 +-
src/fe_utils/string_utils.c | 6 +-
src/interfaces/ecpg/pgtypeslib/numeric.c | 6 +-
src/interfaces/ecpg/preproc/descriptor.c | 3 +-
src/interfaces/libpq/fe-auth-scram.c | 33 ++--
src/interfaces/libpq/fe-auth.c | 18 +-
src/interfaces/libpq/fe-connect.c | 211 ++++++++----------------
src/interfaces/libpq/fe-exec.c | 6 +-
src/interfaces/libpq/fe-print.c | 23 +--
src/interfaces/libpq/fe-secure-common.c | 3 +-
src/port/getaddrinfo.c | 3 +-
38 files changed, 214 insertions(+), 436 deletions(-)