Capsicumize fsck_ffs

[shubh]

Summary

• Entered the capability mode after the setup() call is finished, because the setup() call is used in fsck_msdosfs, and hence it could interfere
• Leveraged cap_pwd and cap_sysctl
• Testing sysctl calls was tough, hence used the casper equivalents for all of them

Test Plan

• Tamper a filesystem using fsdb, then test fsck_ffs

[oshogbo]

sbin/fsck_ffs/dir.c

54

Maybe include it in fsck.h with casper.

sbin/fsck_ffs/fsck.h

297

extra line.

sbin/fsck_ffs/main.c

762

Maybe casper_init?

778

This style look weired.

782

Hym does it works? You limit to one sysctl name and then used with multiple diffrent names like:
vfs.ffs.setcwd, vfs.ffs.setdotdot.