Address Coverity warnings in keymgr.c
Coverity showed that the return value of dst_key_gettime
was
unchecked in INITIALIZE_STATE. If DST_TIME_CREATED was not set we
would set the state to be initialized to a weird last changed time.
This would normally not happen because DST_TIME_CREATED is always set. However, we would rather set the time to now (as the comment also indicates) not match the creation time.
The comment on INITIALIZE_STATE also needs updating as we no longer always initialize to HIDDEN.
(cherry picked from commit 564f9dca)
Closes #1737 (closed)