Build: Avoid building iotivity with -DDEBUG in debug mode
Build: Avoid building iotivity with -DDEBUG in debug mode

iotivity's debug funcionality defines a log level of DEBUG in an enum of log
levels. This gets replaced by an empty string if the DEBUG macro is defined,
causing a syntax error. Thus, we must remove -DDEBUG from the compiler flags.

zqzhang/iotivity-node,zolkis/iotivity-node,zolkis/iotivity-node,zolkis/iotivity-node,zqzhang/iotivity-node,zqzhang/iotivity-node,zqzhang/iotivity-node,zqzhang/iotivity-node,zolkis/iotivity-node,zolkis/iotivity-node