Add sdlgfx.mli files (fixes, doc compilation)
Add sdlgfx.mli files (fixes, doc compilation)

fccm/OCamlSDL1,ocamlsdl/OCamlSDL,ocamlsdl/OCamlSDL,fccm/OCamlSDL1,ocamlsdl/OCamlSDL,fccm/OCamlSDL1,fccm/OCamlSDL1