proc/env DATA_PTR is never NULL

* proc.c (proc_free): remove, use RUBY_TYPED_DEFAULT_FREE
  (proc_mark, proc_memsize): remove needless branching

* vm.c (env_free): remove, use RUBY_TYPED_DEFAULT_FREE
  (env_mark, env_memsize): remove needless branching

This shows a tiny ~0.5% improvement in benchmark/bm_vm2_newlambda.rb
but also removes a lot of code.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47564 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
vm.c (thread_alloc): remove needless volatile

If we needed a volatile there, every other alloc function would need it.
There is nothing special I can see about thread_alloc which would
justify it.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47565 b2dd03c8-39d4-4d8f-98ff-823fe69b080e