vm_core.h: extract VM_STACK_OVERFLOWED_P

* vm_core.h (VM_STACK_OVERFLOWED_P, WHEN_VM_STACK_OVERFLOWED): extract
  condition from CHECK_VM_STACK_OVERFLOW.

* vm_exec.c (vm_stack_overflow_for_insn): move rb_bug call.

* vm_exec.h (CHECK_VM_STACK_OVERFLOW_FOR_INSN): share the condition
  with CHECK_VM_STACK_OVERFLOW.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43702 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-11-18

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43703 b2dd03c8-39d4-4d8f-98ff-823fe69b080e