foc: SVN revision r56

Genode side of the update.

Issue #819
l4linux: Update to L4Linux l4box 3.9.0-l4-svn37

This is the Genode side of the L4Linux update to r37. I also moved L4Linux
sources to GitHub.

Issue #819
noux: Keep track of how dataspaces are used

This patch eliminates the "no attachment at..." warnings, which
were caused by a use-after-free problem of dataspaces. When a
dataspace was destroyed, the users of the dataspace were not
informed and therefore could not revert possible attachments to
RM sessions. The fix introduces a callback mechanism that allows
dataspace users (i.e., RM regions) to register for the event that
a dataspace vanishes.

The following types of dataspaces are handled:
* RAM dataspaces
* ROM dataspaces
* The process binary
* The binary of the dynamic linker
* Args dataspace
* Sysio dataspace
* Env dataspace
* managed RM dataspaces

The handling of ROM dataspaces is still not complete. When forking,
the ROM dataspace of the parent process gets just reused without
creating proper meta data ('Dataspace_info') for the forked process.
Similar issues might arise from other special dataspaces (e.g.,
args, env, sysio).

This patch removes all "no attachment at..." warnings except for
one (an attachment at 0).

Issue #485