Linux 3.13 compat: Remove unused flags variable from __cv_init()

GCC 4.8.1 complained about an unused flags variable when building
against Linux 2.6.26.8:

/var/tmp/portage/sys-kernel/spl-9999/work/spl-9999/module/spl/../../module/spl/spl-condvar.c:
In function ‘__cv_init’:
/var/tmp/portage/sys-kernel/spl-9999/work/spl-9999/module/spl/../../module/spl/spl-condvar.c:39:6:
error: variable ‘flags’ set but not used
[-Werror=unused-but-set-variable]
  int flags = KM_SLEEP;
        ^
	cc1: all warnings being treated as errors

Additionally, the superfluous code uses a preempt_count variable that is
no longer available on Linux 3.13. Deleting the unnecessary code fixes a
Linux 3.13 compatibility issue.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #312
Linux 3.13 compat: Pass NULL for new delegated inode argument

This check was originally added for SLES10, a093c6a, to check for
a 'struct vfsmount *' argument which they added.  However, since
SLES10 is based on a 2.6.16 kernel which is no longer supported
this functionality was dropped.  The checks were refactored to
support Linux 3.13 without concern for historical versions.

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #312