power.c: add O_CLOEXEC on wakelocks

Ensure that FDs associated with /sys/power/wake_lock and
/sys/power/wake_unlock are closed on exec.

(cherrypicked from b3624b26b2a55f33326c794565dd07d5078c655c)

Change-Id: Ia2c8937cf6a1fdd6564fad4785642934c805cf22
1 file changed