selcommands: fix the exception when parsing SEL timestamp

(1) Fix the problem caused by casting to mismatched size that time_t
is 8 bytes.
(2) Change to use thread-safe APIs to covert the timestamp.

Change-Id: Iac86f636b049ff82bb0df2410afb860436dc882c
Signed-off-by: Cosmo Chou <cosmo.chou@quantatw.com>
1 file changed