[test suite] added strtol_wrapper() fault injection tags
[server] check fiu_enable() return value in --fault-injection mode
[libfko] removed fko_new_strdup() fault injection tag since fko_destroy() isn't called
[test suite] added suppressions to fko-wrapper/run_valgrind.sh
[test suite] consolidate valgrind success/failure criteria into a single function
[test suite] add valgrind suppressions for libfiu