Fix complains from clang:

fastnetmon.cpp:2078:28: warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
    if (found_patrica_node = patricia_search_best(lookup_tree, &prefix_for_check_adreess)) {
        ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fastnetmon.cpp:2078:28: note: place parentheses around the assignment to silence this warning
    if (found_patrica_node = patricia_search_best(lookup_tree, &prefix_for_check_adreess)) {
                           ^
        (                                                                                )

Yep, we can compile with clang now on Debian 7 Wheezy!