LU-2600 osd-zfs: batched object accounting

using dsl_sync_task_do_nowait() we can schedule the updates
to be executed in a closing txg. this way object accounting
can be done in memory and then updated in ZAPs once per txg.

Test-Parameters: fortestonly envdefinitions=SLOW=yes,ENABLE_QUOTA=yes \
mdtfilesystemtype=zfs mdsfilesystemtype=zfs ostfilesystemtype=zfs testlist=sanity-quota
Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Change-Id: Iebe96c9847c6c53b8232295a44fd8044b1ae18b4
Reviewed-on: http://review.whamcloud.com/7157
Tested-by: Jenkins
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>
LU-3953 build: cache the results of configure between runs

This modification allow configure script cache the results of
heavy (required compilation) configure tests run on this system
so they can be shared between configure scripts and configure
runs, see configure's option --config-cache. This is very useful
for several configurations on the same machine with different
--enable/disable options.

The time of first clean pass:
  time ./configure -C
  real    1m9.879s
  user    0m33.390s
  sys     0m30.392s

The time of second pass with cached results:
  time ./configure -C
  real    0m10.190s
  user    0m2.900s
  sys     0m4.832s

Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Change-Id: I41b8091331e8f5260262829ad3e24f34ee34c76b
Reviewed-on: http://review.whamcloud.com/9582
Tested-by: Jenkins
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Brian J. Murrell <brian.murrell@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>