parse_build_log: handle "Agent idle before recipe expected to complete"

parse_build_log.pl currently fails to determine the reason for a failure on "Agent idle before recipe expected to complete".

scripts/generic/parse_build_log.pl --summarize http://testresults.qt-project.org/ci/Qt5_master_Integration/build_00547/macx-clang_OSX_10.7/log.txt.gz

Actual output: nothing

Expected output: the "Agent idle before recipe expected to complete" line, and a note that a CI admin should be contacted.