This update breaks some C++ implementations (see [1] and
05ed2cb76b).
All packages that depend on libmicrohttpd have been checked; all but two
(psensor and retroshare) build against libmicrohttpd >= 0.9.71 by now,
and those two are easy enough to patch.
The relevant change is just switching some API return types from `int`
to an enum with the same values, so there isn't any concern about ABI
compatibility with the change (and in fact it's only a warning on a C
compiler).
[1] https://github.com/kismetwireless/kismet/issues/281
a6f4c6166b