ram_blk: remove superfluous block_number check

block_number is Block::sector_t (uint64_t), which never can by less
than 0.
dde_rump: fix compiler int cast warning

Use long instead of int.
dde_rump: implement rumpuser_dprintf()

Though we do not need this function, it is helpful while debugging.
dde_rump: move memcpy() to rump lib

On ARM in one way or another 'string.h' prototypes will be used. Move
the definitions from rump_fs to the rump library because it is needed
by all rump based servers running on ARM.
tool: add makefile for building rumpkernel tools

The rumpkernel tools are used within the Genode OS Framework tool chain.
tool: rump wrapper script
dde_rump: block encryption server using cgd(4)
ports: simple file system test running in noux

By running one of these run scripts a user-defined shell script will
be executed within in noux, which conducts the defined file systems
tests for given File_system_session based file system.
ports: add fs test script using rump_cgd + rump_fs