bignum.c: redundant expression

* bignum.c (LSHIFTX): remove redundant never-true expression.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41611 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
bignum.c: suppress warning

* bignum.c (big2ulong): suppress shorten-64-to-32 warning.  BDIGIT can
  be bigger than long now.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41612 b2dd03c8-39d4-4d8f-98ff-823fe69b080e