some coverity fixes plus fix fdx help (#328) * coverity fixes cmdhflegic- indications are the i in calls to data_buf[i] could = 1052 and overflow the array. cmdhfmfhard - +1 to add space for string null terminator - should we add the 0 terminator value too? reveng.c - memory leak util.c - fix potential overflow of array buf[] util_posix.c - possible integer overflow * fix help errors * fix sprint_hex_ascii again and this function is not even used anywhere... yet...