Relax group descriptor checking for FLEX_BG

Relax group descriptor checking for FLEX_BG

The FLEX_BG feature allows the inode table, block bitmap, and inode
bitmaps to be located anywhere in the filesystem.  Update e2fsck and
libext2fs's checking code to recognize this.

Signed-off-by: Jose R. Santos <jrs@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
--

 e2fsck/super.c          |   14 ++++++++++++--
 lib/ext2fs/check_desc.c |   15 +++++++++++++--
 2 files changed, 25 insertions(+), 4 deletions(-)