sprintf.c: improve rational 'f' format
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47588 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
sprintf.c: improve rational 'f' format
values. [fix GH-717]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47588 b2dd03c8-39d4-4d8f-98ff-823fe69b080e