rump: Initial commit

Build rump libraries within the Genode build system.
rump: Link against rump library
rump: Implement back-end allocator

First try of generalizing the dde_linux-memory allocater. Task: try to get it
into dde_kit
rump: Init finshed
rump: Keep additional initialization sections

Rump libraries have special sections for modules and so called rump components
during startup. Make sure to keep these sections during shared library linkage.
rump: Add DL interface and bootstrapping code
rump: File info with ram_fs
base: Make 'LD_SCRIPT_SO' overwritable
ram_blk: Writable loopback device
ram_blk: Fix copy direction
rump: Basic block-session back end
rump: I/O bio_done debugging
rump: VBFS working
rump: Put all file systems into rump_fs library
rump: Code cleanup
rump: Add file-system sync support
rump: Initial FS server
rump: Add errno support
rump: First working FS server

TODO: Add symlink, unlink, and move support.
libc: 'readlink' returns non-zero terminated buffer

Make so to handle zero termination correctly for 'stat' calls and for debugging
output.