MFC r340130, r340134:

r340130: (by oshogbo)

libcapsicum: Introduce caph_{rights,ioctls,fcntls}_limit

The idea behind those functions is not to force consumers to remember that there
is a need to check errno on failure. We already have a caph_enter(3) function
which does the same for cap_enter(2).

r340134: (by oshogbo)

Fix a recusive call introduce in the r340130.