ChangeLog, e2fsck.h, journal.c, problem.c, problem.h, super.c:

ChangeLog, e2fsck.h, journal.c, problem.c, problem.h, super.c:
  super.c (check_super_block): Be more strict on checking
  	s_r_blocks_count superblock field.
  problem.c, problem.h (PR_0_JOURNAL_UNSUPP_ROCOMPAT,
  	PR_0_JOURNAL_UNSUPP_INCOMPAT, PR_0_JOURNAL_RESET_COMPAT): New problem
  	codes.
  journal.c (e2fsck_journal_load): Use a problem code to report
  	unsupported feature flags.  There is code to clear unsupported flags,
  	but since this is dangerous, it's not allowed in the problem code
  	table.
  journal.c (e2fsck_journal_reset_super): initialize the journal
  	sequence number to a random value to avoid recovering bad transactions
  	from a corrupt journal.