byterun/caml/memory.h cleanup
byterun/caml/memory.h cleanup

Protect private code with the #ifdef CAML_INTERNALS rather than <private> tag.

Thus, the protected code will be included in the installed version
of memory.h but should not be compiled when the header is included
in user code.

gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml