MFC r222950 (gibbs):

MFC r222950 (gibbs):

Remove C constructs that are incompatible with C++ from various
OpenSolaris and ZFS header files.  These changes are sufficient
to allow a C++ program to use the libzfs library.

Note: The majority of these files already included 'extern "C"'
      declarations, so the intention of providing C++ compatibility
      already existed even if it wasn't provided.

cddl/compat/opensolaris/include/assert.h:
	Wrap our compatibility assert implementation in
	'extern "C"'.  Since this is a compatibility header
	I matched the Solaris style of doing this explicitly
	rather than rely on FreeBSD's __BEGIN/END_DECLS macro.

sys/cddl/compat/opensolaris/sys/kstat.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/arc.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dsl_pool.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/ddt.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa.h:
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h:
	Rename parameters in function declarations that conflict
	with C++ keywords.  This was the solution preferred by
	members of the Illumos community.

sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zfs_ioctl.h:
	In C, nested structures are visible in the global namespace,
	but in C++, they take on the namespace of the structure in
	which they are contained.  Flatten nested structure
	definitions within struct zfs_cmd so these structures are
	visible in the global namespace when compiled in both
	languages.

Sponsored by:	 Spectra Logic Corporation

git-svn-id: svn://svn.freebsd.org/base/stable/8@246577 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f