Create a separate script to generate osreldate.h rather than sourcing
newvers.sh into a temporary subshell with inline make rules.

Using a separate script fixes a variety of problems, including establishing
the correct dependencies in the makefiles.  It also eliminates a problem
with the way newvers.sh uses `realpath $0`, because $0 expands differently
within a script sourced into a rule in a makefile depending on the version
of make and of /bin/sh being used.  The latter can cause build breakage in a
cross-build environment, and can also make it difficult to compile 10.0 on
older pre-10.0 systems.

PR:		160646 174422
Submitted by:	Garrett Cooper <yaneurabeya@gmail.com>
Approved by:	re (gjb)
MFC after:	2 weeks
Give argtype struct names a different prefix than probe struct names.
Otherwise it's possible to declare SDT probes in such a way that a name
collision occurs, causing an unexpected compilation error.

Approved by:	re (gjb)
MFC after:	1 week
Omit "__restrict" when generating syscall argument strings. DTrace doesn't
handle it and cannot determine the argument type when it's present.

Approved by:	re (gjb)
MFC after:	1 week
Regenerate syscall argument strings after r255777.

Approved by:	re (gjb)
MFC after:	1 week
Set props and correct RCS ID tag.

Approved by:	re (blanket)