vm_core.h (rb_env_t): use flexible array

* vm_core.h (rb_env_t): use flexible array
  This reduces allocations and speeds up the lambda calculus
  fizzbuzz (bm_app_lc_fizzbuzz.rb) benchmark [ruby-core:64858]
* proc.c (get_local_variable_ptr): deconst to adjust for flex array
* vm.c (env_mark, env_free, env_memsize): remove check for env->env
* vm.c (env_alloc): single allocation for flex array
* vm.c (vm_make_env_each): adjust env_alloc call

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47453 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-09-09

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47454 b2dd03c8-39d4-4d8f-98ff-823fe69b080e