in non-void -> void. add prefix void_

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
Insert prototypes

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
implement stubs

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
Merge branch 'feature/fix-non-void' into develop