Tweaks in load_skiplist()

Tweaks in load_skiplist()

If there's an issue opening the default skip list file other than its
absence (most likely bad permissions), we should not silently ignore
that. Also, use err() instead of errx() to display the error.

Second, linelen, the return value of getline(), is not currently used.
Repurpose it to save the result of strcspn() which calculates the length
of the string we're interested in and use that instead of strlen().

ok claudio