CTestCoverageCollectGCOV: Capture gcov output in log file
The output of gcov can be large and we only display it in a failure case. Put it in a log file to avoid accumulating large output in memory.
Also avoid capturing gcov output in QUIET mode. The QUIET
mode suppresses any mention of our logged output, so do not bother logging it. This also provides a way for users to avoid saving possibly large output on disk.
Fixes: #20554 (closed)
Edited by Brad King