https://bugs.winehq.org/show_bug.cgi?id=40317
--- Comment #22 from Vincent Povirk madewokherd@gmail.com --- Apparently, in wheezy's mingw-w64, inet_pton is in the library but not declared in the headers. Probably the correct fix is to add a configure check to Mono for the declaration. Until then, I don't have a work-around.
You can try the official build at https://dl.winehq.org/wine/wine-mono/4.6.2/