pgsql: Fix memory leaks from incorrect strsep() uses

Fix memory leaks from incorrect strsep() uses

Commit 5d2e1cc117b introduced some strsep() uses, but it did the
memory management wrong in some cases. We need to keep a separate
pointer to the allocate memory so that we can free it later, because
strsep() advances the pointer we pass to it, and it at the end it
will be NULL, so any free() calls won't do anything.

(This fixes two of the four places changed in commit 5d2e1cc117b. The
other two don't have this problem.)

Reported-by: Alexander Lakhin <exclusion(at)gmail(dot)com>
Discussion: https://www.postgresql.org/message-id/flat/79692bf9-17d3-41e6-b9c9-fc8c3944222a(at)eisentraut(dot)org

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/4b652692e97923298d0c7b9c1c303fc648984d92

Modified Files
--------------
src/common/logging.c | 3 ++-
src/test/regress/pg_regress.c | 7 +++++--
2 files changed, 7 insertions(+), 3 deletions(-)