update magic numbers

Numbers and .mlbuild and .mlp were not always synchronized; I only
changed the typedtree-related numbers, but used the max of both +1 on
both sides -- the .cm{o,a,x}... numbers are still non-synchronized.

From: Gabriel Scherer <gabriel.scherer@gmail.com>

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15586 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
bootstrap

From: Gabriel Scherer <gabriel.scherer@gmail.com>

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15587 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Sys: Use constant for some runtime limitations.

It allows to have non-standard limits for non-standard runtime.
ie: js_of_ocaml use 32bits integer, and can handle
string much bigger than 16Mo.

From: Hugo Heuzard <hugo.heuzard@gmail.com>

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@15588 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02