* gc.c: invoke GC before memory allocation (xmalloc/xrealloc)
  when GC.stress = true.
  [Bug #9859]
* test/ruby/test_gc.rb: add a test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46399 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-06-11

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46400 b2dd03c8-39d4-4d8f-98ff-823fe69b080e