Description of problem:
When somebody runs blkparse with non-existent file as argument, it does not
complain. Exit code is zero.
This bug is similar to bz#499581 , but it involves blkparse instead of blkrawverify.

Version-Release number of selected component (if applicable):
blktrace-1.0.0-5.el5

How reproducible:
always

Steps to Reproduce:
# df -l
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
                      73545144   2242708  67506264   4% /
/dev/sda1               101086     12445     83422  13% /boot
tmpfs                   513200         0    513200   0% /dev/shm
# blktrace -d /dev/sda -w 10
Device: /dev/sda
  CPU  0:                    0 events,        1 KiB data
  CPU  1:                    0 events,        2 KiB data
  Total:                     0 events (dropped 0),        2 KiB data
# ls -l *.blktrace.*
-rw-r--r-- 1 root root  464 May 11 04:35 sda.blktrace.0
-rw-r--r-- 1 root root 1488 May 11 04:35 sda.blktrace.1
# rm -f *.blktrace.*
# blkparse -i sda

Throughput (R/W): 0KiB/s / 0KiB/s
Events (sda): 0 entries
Skips: 0 forward (0 -   0.0%)
# echo $?
0
#
  
Actual results:
no error message appears
exit code == 0

Expected results:
an error message appears (e.g. "no sda* files found")
exit code != 0