Set variables to avoid false-positive compiler warnings.
../tool/transport_common.cc:429:14: error: ‘code_250’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
(I don't believe it can actually happen though.)
Change-Id: I78d19ad42ed4c05404f1d8d3e8f254ede3244b8d