* bignum.c (LSHIFTX): Revert r41611.
  The redundant expression suppresses a warning, C4293, by Visual
  Studio.
  http://ruby-mswin.cloudapp.net/vc10-x64/ruby-trunk/log/20130625T072854Z.log.html.gz#miniruby



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41620 b2dd03c8-39d4-4d8f-98ff-823fe69b080e