tune2fs: respect quota config option

tune2fs: respect quota config option

If we haven't turned --enable-quota on at config time,
I don't think tune2fs should know about the feature either.

Today we can actually tune2fs -O quota even if not
configured on, and then the rest of the tools will
refuse to touch it:

# tune2fs -O quota /dev/sda1
# tune2fs -O ^quota /dev/whatever complains
tune2fs 1.42.3 (14-May-2012)
tune2fs: Filesystem has unsupported read-only feature(s) while trying to open /dev/sda1
# fsck /dev/sda1
fsck from util-linux 2.21.2
e2fsck 1.42.3 (14-May-2012)
/dev/sda1 has unsupported feature(s): quota
e2fsck: Get a newer version of e2fsck!

Ok, so turn it off?
# tune2fs -O ^quota /dev/whatever complains
tune2fs 1.42.3 (14-May-2012)
tune2fs: Filesystem has unsupported read-only feature(s) while trying to open /dev/sda1

Nope.  Debugfs?  Nope.

# debugfs -w /dev/sda1
debugfs 1.42.3 (14-May-2012)
/dev/sda1: Filesystem has unsupported read-only feature(s) while opening filesystem

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reported-by: Bert DeKnuydt <Bert.Deknuydt@esat.kuleuven.be>
Addresses-Red-Hat-Bugzilla: #880596
Signed-off-by: Theodore Ts'o <tytso@mit.edu>