12181 zvol swap tests should avoid grep -w

*** 26,35 ****
--- 26,36 ----
  #
  
  #
  # Copyright (c) 2013, 2016 by Delphix. All rights reserved.
  # Copyright 2016 Nexenta Systems, Inc.
+ # Copyright 2020 Joyent, Inc.
  #
  
  . $STF_SUITE/include/libtest.shlib
  . $STF_SUITE/tests/functional/zvol/zvol_common.shlib
  
*** 52,62 ****
          typeset dumpdev=$(get_dumpdevice)
          if [[ $dumpdev != $savedumpdev ]] ; then
                  safe_dumpadm $savedumpdev
          fi
  
!         swap -l | grep -w $voldev > /dev/null 2>&1
          if (( $? == 0 ));  then
                  log_must swap -d $voldev
          fi
  
          typeset snap
--- 53,64 ----
          typeset dumpdev=$(get_dumpdevice)
          if [[ $dumpdev != $savedumpdev ]] ; then
                  safe_dumpadm $savedumpdev
          fi
  
!         swap -l | awk 'NR > 1 { print $1 }' | \
!             grep "^$voldev\$" > /dev/null 2>&1
          if (( $? == 0 ));  then
                  log_must swap -d $voldev
          fi
  
          typeset snap