gh-2763 Fix valgrind error running compiler test suite
gh-2763 Fix valgrind error running compiler test suite

Make sure that log handler is cleared before closing the log file.

Fixes gh-2763.

Signed-off-by: Richard Chapman <5900d56196fe29dba8e3ae556d57eae28e9f0195@hpccsystems.com>

afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform