[bugfix] Distribute and install git-whitespace-hook.

git-whitespace-hook is called by dune-control which barks if
it is not available. Therefore we distribute and install after
this patch.
(cherry picked from commit f5c8b4903df6e5be1dac4f258a328449e6483954)

Signed-off-by: Markus Blatt <markus@dr-blatt.de>
[autotools,bugfix] Feed include path of all modules to dune-autogen

Previously only the include path of the local modules were used. This
caused errors with installed dune-common modules, similar to:

--> aclocal...

Error: Could not find dune-common/am!
Usage: dune-autogen DUNE_MODULE_PATH_LIST [options]
  --ac=, --acversion=VERSION   use a specific VERSION of autoconf
  --am=, --amversion=VERSION   use a specific VERSION of automake
  -h,    --help                you already found this :-)
--- Failed to build dune-typetree ---
Terminating dunecontrol due to previous errors!

This is also related to https://dune-project.org/flyspray/index.php?do=details&task_id=891

With this patch we include the aclocal, m4 or am directory of all modules
(installed and local ones) and everything works again as exspected.
(cherry picked from commit c57e60371d60bdf5a530b6a3b3471878c4dcb44d)

Signed-off-by: Markus Blatt <markus@dr-blatt.de>