* ext/objspace/object_tracing.c: Add experimental methods to dump
objectspace as json: ObjectSpace.dump_all and ObjectSpace.dump(obj).
These methods are useful for debugging reference leaks and memory growth
in large ruby applications. [Bug #9026] [ruby-core:57893] [Fixes GH-423]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43585 b2dd03c8-39d4-4d8f-98ff-823fe69b080e