btrfs-progs: Fix stack overflow for checking qgroup on tree reloc tree

btrfs-progs: Fix stack overflow for checking qgroup on tree reloc tree

For tree reloc tree whose level is >= 2, the root node's parent will
point to itself.
In this case it will make btrfsck overflow its stack and cause segfault.

While for tree reloc tree, it doesn't affect qgroup and kernel can
handle it well.

So add tree reloc tree check for qgroup-verify.c and fix the bug.

Test case will follow soon after I make a minimal image for it.
Current xz ziped image is still over 10M for a 512M fs.

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