e2fsck: Add test code in problem.c to verify problem codes

e2fsck: Add test code in problem.c to verify problem codes

We've hit a number of cases where the error codes in problem.h have
been assigned duplicate values compared to problems in our own e2fsck
patches, and this can lead to confusing and difficult to find bugs
in e2fsck (e.g. wrong problem messages, incorrect repair action, etc).

Attached is a test case for the problem.c file to ensure that the
problem table is sorted and does not contain any duplicate values.
Having the problem table sorted allows the correctness checking to be
very simple, and if it ever became important for performance we could
use binary searching of the problem table for the specific problem code.

Signed-off-by: Andreas Dilger <adilger@sun.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>