lib/syscall_shim: Pretty-print format: clone

lib/syscall_shim: Pretty-print format: clone

This commit introduces initial print format and decoding definitions for
the following system calls: `SYS_clone`

Checkpatch-Ignore: MISSING_BREAK
Signed-off-by: Simon Kuenzer <simon@unikraft.io>
Reviewed-by: Eduard Vintilă <eduard.vintila47@gmail.com>
Reviewed-by: Andra Paraschiv <andra@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #737