ifdef ext2_print_inode which is not really used.

ext2_print_inode is not really used but it was nice to
have for initial development work. #ifdef it under a
new EXT2FS_DEBUG knob so that we don't spend time
compiling it.

MFC after:	3 days


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274437 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f