gc.c: use size_t

* gc.c (ruby_gc_params_t, get_envparam_size): use size_t for
  integer environment parameters for sizes.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44871 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
explicitly stop DRb::ExtServ

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44872 b2dd03c8-39d4-4d8f-98ff-823fe69b080e