generic/448: define BASE_TEST_FILE before _cleanup

NFS v4.2 supports SEEK_DATA and SEEK_HOLE, but earlier versions do
not.  As a result, the test exits and runs the cleanup function
without the $BASE_TEST_FILE variable set and the shell expands it to
"rm -f .*", deleting all hidden files in the current directory.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/generic/448

@@ -15,9 +15,12 @@ tmp=/tmp/$$
 status=1    # failure is the default!
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
+BASE_TEST_FILE=$TEST_DIR/seek_sanity_testfile_$seq
+
 _cleanup()
 {
-	rm -f $tmp.* $BASE_TEST_FILE.*
+	cd /
+	rm -f $tmp.* $BASE_TEST_FILE
 }
 
 # get standard environment, filters and checks
@@ -30,8 +33,6 @@ _supported_os Linux
 _require_test
 _require_seek_data_hole
 
-BASE_TEST_FILE=$TEST_DIR/seek_sanity_testfile_$seq
-
 _require_test_program "seek_sanity_test"
 
 _run_seek_sanity_test -s 18 -e 18 $BASE_TEST_FILE > $seqres.full 2>&1 ||