Fix wscript to compile crc32.cpp.
Fix wscript to compile crc32.cpp.

When crc32.cpp was not compiled when --enable-zookeeper is not specified, but crc32.cpp is used always.

roselleebarle04/jubatus,Asuka52/jubatus,kmaehashi/jubatus,gintenlabo/jubatus,kmaehashi/jubatus,jubatus/jubatus,mathn/jubatus,gintenlabo/jubatus,rimms/jubatus,elkingtonmcb/jubatus,rimms/jubatus,Asuka52/jubatus,jubatus/jubatus,jubatus/jubatus,mathn/jubatus,roselleebarle04/jubatus,elkingtonmcb/jubatus