custom_query performance data duplication

[petere]

When custom_query returns multiple rows, their performance data string is duplicated in subsequent rows. For example:

./check_postgres.pl --action=custom_query --dbname=postgres --dbuser=peisentraut --warning=100 --query="select 30 as result, 'foo' as data union select 20, 'bar' union select 10, 'baz' order by 1 desc"

POSTGRES_CUSTOM_QUERY OK: DB "postgres" 30 * 20 * 10 | time=0.08s data=foo;100 time=0.08s data=foo;100 data=bar;100 time=0.08s data=foo;100 data=bar;100; data=baz;100

Correct would be

POSTGRES_CUSTOM_QUERY OK: DB "postgres" 30 * 20 * 10 | time=0.08s data=foo;100 time=0.08s data=bar;100 time=0.08s data=baz;100

The fix appears to be to change line 4100

$db->{perf} .= sprintf ' %s=%s;%s;%s',

to

$db->{perf} = sprintf ' %s=%s;%s;%s',