dtrace tests: fix prototypes for gcc build

- quiet -Wstrict-prototypes
- provide prototypes for weak aliases

Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D28036

Address compiler warnings in C code used by the DTrace test suite.

Reported by: Jenkins
MFC after: 1 week

Include required headers in DTrace test programs.

MFC after: 1 week

Implement a workaround to allow this test program to be compiled with clang.
It seems that if a pragma is used to define a weak alias for a local
function, the pragma must appear after the function is defined.

PR: 193056
MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

- Import the HEAD csup code which is the basis for the cvsmode work.