* bignum.c (big2str_base_powerof2): New function.
  (rb_big2str0): Use big2str_base_powerof2 if base is 2, 4, 8, 16 or 32.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41194 b2dd03c8-39d4-4d8f-98ff-823fe69b080e