* bignum.c (big2str_alloc): New function to allocate the result string. 
  It is called after actual length is calculated.
  (big2str_struct): Add fields: negative, result and ptr.
  (big2str_orig): Write out the result via b2s->ptr.
  (big2str_orig): Ditto.
  (rb_big2str1): Don't allocate the result string at beginning.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42303 b2dd03c8-39d4-4d8f-98ff-823fe69b080e