Retire legacy test infrastructure

* Removed zpios kmod, utility, headers and man page.

* Removed unused scripts zpios-profile/*, zpios-test/*,
  zpool-config/*, smb.sh, zpios-sanity.sh, zpios-survey.sh,
  zpios.sh, and zpool-create.sh.

* Removed zfs-script-config.sh.in.  When building 'make' generates
  a common.sh with in-tree path information from the common.sh.in
  template.  This file and sourced by the test scripts and used
  for in-tree testing, it is not included in the packages.  When
  building packages 'make install' uses the same template to
  create a new common.sh which is appropriate for the packaging.

* Removed unused functions/variables from scripts/common.sh.in.
  Only minimal path information and configuration environment
  variables remain.

* Removed unused scripts from scripts/ directory.

* Remaining shell scripts in the scripts directory updated to
  cleanly pass shellcheck and added to checked scripts.

* Renamed tests/test-runner/cmd/ to tests/test-runner/bin/ to
  match install location name.

* Removed last traces of the --enable-debug-dmu-tx configure
  options which was retired some time ago.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6509

scripts/zloop.sh

@@ -20,11 +20,10 @@
 # Copyright (C) 2016 Lawrence Livermore National Security, LLC.
 #
 
-basedir=$(dirname "$0")
-
+BASE_DIR=$(dirname "$0")
 SCRIPT_COMMON=common.sh
-if [ -f "${basedir}/${SCRIPT_COMMON}" ]; then
-	. "${basedir}/${SCRIPT_COMMON}"
+if [ -f "${BASE_DIR}/${SCRIPT_COMMON}" ]; then
+	. "${BASE_DIR}/${SCRIPT_COMMON}"
 else
 	echo "Missing helper script ${SCRIPT_COMMON}" && exit 1
 fi