libevent: remove unnecessary CONSTCOND comments

Since lint1/tree.c 1.202 from 2021-01-31, lint no longer needs the
/*CONSTCOND*/ for do-while-0 "loops".

This reduces the local modifications.

No fu

libevent: remove unnecessary CONSTCOND comments

Since lint1/tree.c 1.202 from 2021-01-31, lint no longer needs the
/*CONSTCOND*/ for do-while-0 "loops".

This reduces the local modifications.

No functional change.

show more ...

Merge local changes from libevent 2.1.8 and 2.1.12

merge conflicts

Simplify.

merge and update manpages and include/event2/event-config.h
May need extra fixing around log-internal.h and log.c

Fix memcmp use.

merge conflicts, make compile with warnings.

import libevent 2.x