random.c: increase limit for generic rand
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39466 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
random.c: increase limit for generic rand
rand method should return a number less than it, so increase for the
difference. [ruby-core:52779] [Bug #7935]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39466 b2dd03c8-39d4-4d8f-98ff-823fe69b080e