* random.c (rand_init): Add a cast to fix clang compile error:
  random.c:410:32: error: implicit conversion loses integer precision:
  'size_t' (aka 'unsigned long') to 'int' [-Werror,-Wshorten-64-to-32]
  This cast doesn't cause a problem because len is not bigger than
  MT_MAX_STATE.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41168 b2dd03c8-39d4-4d8f-98ff-823fe69b080e