pgsql: Fix references to renamed function in comments

Fix references to renamed function in comments

I renamed the function in commit 024c521117, but missed these
comments.

Reported-by: Richard Guo
Discussion: https://www.postgresql.org/message-id/CAMbWs4-jR6qc7JRMKwz-zXQy_AYLUZ3PHjGep4B91of321cqWw@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/ef4cfdce0ef8b926803b0d5ffafef1c42b15bbfb

Modified Files
--------------
src/backend/utils/activity/backend_status.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)