drconfig reports incorrect debug information due to buffer re-use

This was discovered here: https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!topic/dynamorio-users/J0boO-VEZxo

Code inspection shows what looks like a bug where the path to compare to the debug path is clobbered by reusing the same buffer to read a numeric parameter here: https://github.com/DynamoRIO/dynamorio/blob/master/libutil/dr_config.c#L1346 Thus it will always print Debug=no with that bug.