Add patches for system call handling

Add patches for system call handling

Musl wrappers use a binary system call, e.g. for x86_64 the `syscall`
instruction is used which is a trap. In a single-address-space OS as an Unikraft
unikernel this is just overhead. Hence, we changed the way musl deals with
syscall handling by using some syscall shim layer macros.
Those will replace binary system calls with function calls.

Signed-off-by: Dragos Iulian Argint <dragosargint21@gmail.com>
Reviewed-by: Sergiu Moga <sergiu.moga@protonmail.com>
Reviewed-by: Simon Kuenzer <simon@unikraft.io>
Approved-by: Simon Kuenzer <simon@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #5