Ruby

memory_status.rb: independent of MiniTest

• test/lib/memory_status.rb: make Memory::Status independent of
  MiniTest::Skip.
• test/lib/test/unit/assertions.rb (assert_no_memory_leak): skip
  if Memory::Status is not available.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54049 b2dd03c8-39d4-4d8f-98ff-823fe69b080e