big2str_base_powerof2.
(rb_big2str_poweroftwo): New function for test.
(big2str_generic): Extracted from rb_big2str1.
(rb_big2str_generic): New function for test.
* internal.h (rb_big2str_poweroftwo): Declared.
(rb_big2str_generic): Ditto.
* ext/-test-/bignum/big2str.c: New file.
* test/-ext-/bignum/test_big2str.rb: New file.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42758 b2dd03c8-39d4-4d8f-98ff-823fe69b080e