PR#6540: update documentation of default values in gc.mli

(Patch by Daniel Richman)


git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15185 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
PR#6539: don't divide caml_major_heap_increment by the word size

(Patch by Daniel Richman)


git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15186 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02