make regexp used by log parser to find errors in cmd outputs stricter

[boegel]

Currently, the log parser often mentions a (large) amount of potential errors after finishing a build.

Most of the time, this is triggered by false positives, because the regex used by the log parser is not strict enough.

A nice target to aim for is building HPL with goalf/goolf (i.e. the quick demo) without issues false positives, or at least minimizing them as much as possible.