btrfs-progs: fsck-tests: Add test image for overlapping csum item

The image has a csum item overlap with next csum item, make sure btrfs
check can detect it.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

tests/fsck-tests/045-overlap-csum-item/test.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+#
+# Verify that check can detect overlapped csum items
+#
+# There is one report of overlap csum items, causing tree-checker to reject
+# the csum tree.
+#
+# Make sure btrfs check can at least detect such error
+
+source "$TEST_TOP/common"
+
+check_prereq btrfs
+
+check_image() {
+	run_mustfail "overlapping csum item not detected" \
+		"$TOP/btrfs" check "$1"
+}
+
+check_all_images