pgsql: psql: call clearerr() just before printing

psql: call clearerr() just before printing

We were never doing clearerr() on the output stream, which results in a
message being printed after each result once an EOF is seen:

could not print result table: Success

This message was added by commit b03436994bcc (in the pg13 era); before
that, the error indicator would never be examined. So backpatch only
that far back, even though the actual bug (to wit: the fact that the
error indicator is never cleared) is older.

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/8d645a116ef6e04bfb03e259149b8e163dbdf50c

Modified Files
--------------
src/fe_utils/print.c | 3 +++
1 file changed, 3 insertions(+)