tests/int: use gawk where needed

This expression is specific to GNU awk (gawk), so if someone has other version
of awk installed, this won't work and it's not easy to see why.

Explicitly requiring gawk here is better.

Revert "tests/int/helpers: gawk -> awk"

This reverts commit 4e65118.

Reported-by: lifubang <[email protected]>
Signed-off-by: Kir Kolyshkin <[email protected]>

Author: kolyshkin

tests/integration/helpers.bash

@@ -132,7 +132,8 @@ function init_cgroup_paths() {
 		CGROUP_SUBSYSTEMS=$(awk '!/^#/ {print $1}' /proc/cgroups)
 		local g base_path
 		for g in ${CGROUP_SUBSYSTEMS}; do
-			base_path=$(awk '$(NF-2) == "cgroup" && $NF ~ /\<'"${g}"'\>/ { print $5; exit }' /proc/self/mountinfo)
+			# This uses gawk-specific feature (\< ... \>).
+			base_path=$(gawk '$(NF-2) == "cgroup" && $NF ~ /\<'"${g}"'\>/ { print $5; exit }' /proc/self/mountinfo)
 			test -z "$base_path" && continue
 			eval CGROUP_"${g^^}"_BASE_PATH="${base_path}"
 		done