marshal.c: fix marshal_load ivar

* marshal.c (r_object0): copy all instance variables not only generic
  ivars, before calling post proc.  [ruby-core:51163] [Bug #7627]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40408 b2dd03c8-39d4-4d8f-98ff-823fe69b080e