This changeset modifies the VM generator so that vm.inc is written in
C99.  Also added some comments in _insn_entry.erb so that the
intention of each parts to be made more clear.  I think this improves
overall readability of the generated VM.

Confirmed that the exact same binary is generated before/after this
changeset.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66923 b2dd03c8-39d4-4d8f-98ff-823fe69b080e