compile.c: add comments
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48893 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
compile.c: add comments
add comments about inputs and outputs of func.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48893 b2dd03c8-39d4-4d8f-98ff-823fe69b080e