ram_blk: Writable loopback device

Issue #1048
rump: Port of the rump kernels to Genode

For further information see: http://wiki.netbsd.org/rumpkernel/. In this version
I ported the central rump components to Genode in order to take advantage of
NetBSD file system implementation. The new 'dde_rump' repository contains the
Genode version of the rump libraries and a 'rump_fs' server that implements
Genode file-system-session interface. Currently ext2, iso9660, and fat
file-systems are supported.

Issue #1048
usb_drv: Fix implicit declaration warnings

Issue #1050
gdb_monitor: show correct register state on FOC

On Genode/Fiasco.OC, when an unresolved page fault occurs, only the IP and
SP registers are valid in the thread state read by GDB monitor. This was
not taken into account so far and the other (possibly outdated) register
values got reported to the client, too.

With this patch, only IP and SP get reported to the client in the page
fault case.

Fixes #1063.
Noux: fix GDB arguments in run script

Noux generates 'argv[0]' for the initial child automatically (in contrast
to the 'config_args' library), so the first argument stated in the
configuration should not be the GDB program name.

Fixes #1062.
TrustZone: reenable memory protection (fix #1060)
libports: extend FUSE implementation

* add sync method:
  Since file systems tend to have a inbuild caching mechansim we need to
  sync these caches at the end of session when using the fuse_fs server.
  Therefore each FUSE file system port has to implement a Fuse::sync_fs()
  function that executes the necessary actions if requested.

* add symlink check

* allow to check FUSE fs initialization
  This changes the private API of the FUSE implementation. The init_fs
  method now has to return true if the initialization was successful and
  otherwise false. All current users of the API are also changed
  accordingly.

Fixes #1058.
libports: prevent main symbol clash in fuse-ext2

Omit the main rountine in fuse-ext2.c. Otherwise using fuse-ext2 with
fuse_fs is not possible because the server framework already defines
a main routine.

Fixes #1058.
libports: less noisy fuse_ext2 compilation

Fixes #1058.
libports: less noisy libext2fs compilation

Fixes #1058.
libports: less noisy compilation of libfuse

Out of laziness we only provide two dummy functions for all FUSE
operations, which are used in case the FUSE file system does not
implement them itself.

Fixes #1058.
libports: add libc_fuse_ntfs-3g

Fixes #1058.
libports: initial fuse_fs implementation

The fuse_fs server provides access to a FUSE based file system by using
a File_system_session.

Fixes #1058.
rump: Increase FS server stack size