Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

UTFize my name.

- Add include for libutil.h and string.h for prototype.
- Cast the rvalue to be compared with the result of
strlen() to size_t.

Add utility functions for checking if a given kernel module is loaded,
and loading it.