We call memset to zero `mh' a few lines above anyways, making
explicitly zero-ing each field unnecessary.
Compilers optimize this code away anyways, but it still costs me
4 lines of my small terminal and even smaller attention span.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50786 b2dd03c8-39d4-4d8f-98ff-823fe69b080e