tests/int: BATS_TMPDIR -> BATS_RUN_TMPDIR

It's a little known fact, but BATS_TMPDIR is just /tmp, and it is not
being cleaned by bats after the test.

BATS_RUN_TMPDIR (available since bats 1.2.1) is $BATS_TMPDIR/bats-run-$$
(i.e. it is per bats run and includes PID), and it is cleaned up after
the test (unless --no-tmpdir-cleanup is given).

Use BATS_RUN_TMPDIR for better isolation and cleanup.

[v2: check for BATS_RUN_TMPDIR, effectively requiring bats >= 1.2.1]

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/list.bats

@@ -6,7 +6,7 @@ function setup() {
 	unset ALT_ROOT
 	teardown
 	setup_busybox
-	ALT_ROOT=$(mktemp -d "$BATS_TMPDIR/runc-2.XXXXXX")
+	ALT_ROOT=$(mktemp -d "$BATS_RUN_TMPDIR/runc-2.XXXXXX")
 }
 
 function teardown() {