Fix ioctl signature

Fix ioctl signature

The signature of ioctl uses a signed int as second argument. This,
however, differs from the definition in Linux, glibc, and our own
implementation in Unikraft, which use an unsigned long. Since using
int has lead to all sorts of problems (e.g., overflow into sign bit),
this commit adopts unsigned long also for the musl imported
header.

Signed-off-by: Marc Rittinghaus <marc.rittinghaus@unikraft.io>
Reviewed-by: Andra Paraschiv <andra@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #42