Fix mke2fs defaults when /etc/mke2fs.conf doesn't exist

Fix mke2fs defaults when /etc/mke2fs.conf doesn't exist

One of our testers filed a bug that said "mkfs.ext3 is much slower
when mke2fs.conf is missing..."

This is because the shipped defaults in mke2fs.conf do not match the
shipped defaults in the mkfs code itself; he wound up making a 1k
block filesystem on a very large block device, for example.

So - How about this patch, to bring them back into line?  Which makes
me wonder; having "defaults" in 2 different places is bound to get out
of sync; should we instead generate both code & config file defaults
(and maybe man page defaults) from a common source?

Anyway, here's a patch to bring mke2fs.conf and mke2fs.c into line for
current defaults...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>