Use builtin bswap16 of gcc 4.8 (#377)
Use builtin bswap16 of gcc 4.8 (#377)

stephane/libmodbus,OliverDDS/libmodbus,OliverDDS/libmodbus,marinbek/libmodbus,marinbek/libmodbus,stephane/libmodbus,marinbek/libmodbus,OliverDDS/libmodbus,stephane/libmodbus