Hostname and PID are output as a message prefix in many places in
our code. Their printf-formats were either `[%s:%d]` or `[%s:%05d]`.
This commit changes `[%s:%d]` to `[%s:%05d]`. The latter was more
widely used in our code (including OPAL output system and the signal
handler).
Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>