e2fsck: Move check to add an index to a directory after fixing i_size

e2fsck: Move check to add an index to a directory after fixing i_size

The check that determines whether an directory needs to be have an
index added to it depends on i_size.  So move it after we have fixed
up i_size so that we reliable will rehash a directory that needs it,
even if its i_size field was originally incorrect.  Otherwise, a
second run of e2fsck would be needed before the directory gets an
index added.

Thanks to Mikulas Patocka for providing a sample file system which
demonstrated this problem.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>