The async-signal-safe functions to get thread-id
and thread-name, which cache the results, are
faster, cleaner, and signal-safe. No reason why
we shouldn't always use them.
Especially since it appears the logic was
inverted in Log::prefix, such that the signal
un-safe calls were made during signal-handling,
and the safe ones were called otherwise!
Instead of passing the signal-safe flag to
Log::prefix, we pass the buffer size, for
improved security.
Furthermore, reduce header dependencies
and reduce clutter.
Change-Id: I697689b2f0a290b6d8cce4babc3ac1e576141da6
