Missing return value check of `filter_blocked`

[MicroMilo]

fdns/src/fdns/filter.c

Line 562 in 05a9c02

filter_blocked(start, 1, 1);

We can found that the return value of filter_blocked has its meaning.

" return 1 if the site is blocked, 0 if the site is not blocked"

Also by searching the filter_blocked in the repo, we can find only this function call is missing the check.
So I think there is a potential bug here.