miragesdk: move files around

The new hiearchy is:
- pkg/{init,mirage-compile}: additional Moby packages
- src/sdk -> the begining of the MirageOS SDK for Moby
- src/dhcp-client -> the code for the MirageOS dhcp-client service

Signed-off-by: Thomas Gazagnaire <thomas@gazagnaire.org>

projects/miragesdk/src/sdk/jbuild

@@ -6,5 +6,4 @@
               cmdliner fmt.cli logs.fmt logs.cli fmt.tty decompress
               irmin irmin-git irmin-http lwt.unix rawlink tuntap
               irmin-watcher inotify))
-  (preprocess (per_file ((pps (cstruct.ppx)) (ctl))))
  ))