test_array.rb: skip if timed out

* test/ruby/test_array.rb (test_shared_marking): skip if timed out,
  this test can just take a lot of time.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45567 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* array.c: make shared arrays WB-protected objects.
  Shared arrays were WB-unprotected object because
  sharing array can modify shared array's buffer
  if it occupied shared array.
  [sharing array (ary)] -> [shared array (shared)] -> <buff>
                |                                       A
                +---------------------------------------+
             write `buff' with WB(ary, &buff[i], obj)
             -> if `ary' and `shared' are old, then only `ary'
                will be remembered.
             -> traverse from `ary'. But `shared' is old, so
                that written `obj' is not marked.
  It cause WB miss so that shared arrays were WB-unprotected.
  (WB-unprotected objects are marked everytime if it is living)
  This patch insert WB() for `shared' if it is needed.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45568 b2dd03c8-39d4-4d8f-98ff-823fe69b080e