btrfs-progs: Add chunk corrupt funtion to btrfs-corrupt-block

btrfs-progs: Add chunk corrupt funtion to btrfs-corrupt-block

Add chunk corrupt function to btrfs-corrupt-block.
This funtion can be used to delete or corrupt a given chunk or the whole
chunk tree.

This funtion is useful to test the coming chunk recover funtion.

BTW, since the chunk recover funtion is based on whole partion scanning,
so the COW should be disabled and edit leaf without changing generation.
Which makes btrfs_commit_transation giving some ignorable warning.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>