Ruby

rational.c: segfault on Rational exponent

• rational.c (read_num): fix segfault on Rational() with positive
  but less than the length of fractional part exponent. should be
  negated to convert to divisor which is a reciprocal.
  [ruby-core:85783] [Bug #14547]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62555 b2dd03c8-39d4-4d8f-98ff-823fe69b080e