Sanitizers do not create a log file when no defects are found. Therefore,
it is currently impossible for ctest_memcheck to set both
`CAPTURE_CMAKE_ERROR` and `RETURN_VALUE` to zero.


With defects, `CAPTURE_CMAKE_ERROR`=0 and `RETURN_VALUE`=-1, as expected.

With no defects, `CAPTURE_CMAKE_ERROR`=-1 and `RETURN_VALUE`=0.