export caml_major_gc_hook in major_gc.h and document
export caml_major_gc_hook in major_gc.h and document

gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,eliberis/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,yunxing/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,yunxing/ocaml,yunxing/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,eliberis/ocaml,eliberis/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,eliberis/ocaml,eliberis/ocaml