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

GNU/kFreeBSD portability fix. This glue <stdlib.h> overrides header protection
in the system-wide version of <stdlib.h> by wrapping the #include_next
<stdlib.h> within the scope of its own header protection. On FreeBSD this has
no effect, since both header protections are equivalent. However the GNU version
of <stdlib.h> implements a special header protection mechanism which allows it
to be included multiple times (in different modes).

Simply by moving the #include_next off the header protection, we allow
system-wide <stdlib.h> to implement its own protection policy, whichever that
may be.

Forced commit to note that these files were repo copied.

Add more OpenSolaris compatibilty headers.