merge revision(s) 39466,39470: [Backport #7935]

	* random.c (rb_random_ulong_limited): limit is inclusive, but generic
	  rand method should return a number less than it, so increase for the
	  difference.  [ruby-core:52779] [Bug #7935]

	* test/ruby/test_array.rb (test_sample_random): remove adjustment for
	  the bug fixed by r39466.  [ruby-core:52779] [Bug #7935]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39675 b2dd03c8-39d4-4d8f-98ff-823fe69b080e