Sort file names using sorted()

Sort file names using sorted()

- PROBLEM
python's os.listdir() returns a list of files without sorting.
In this case, the list can be different across machines.
As a result, OBS can recognize build results are different everytime
even though the source is unchanged.

- SOLUTION
Use sorted(os.listdir()) instead of os.listdir().

Change-Id: Idf3ba1e51fb790269dafb651347ff84dbda89a10
Signed-off-by: Junghyun Kim <jh0822.kim@samsung.com>