These files were pulled from the 1.6.3 release tarball.
This new version builds against OpenSSL version 1.1 which will be
the default in the new Debian Stable which is due to be released
RealSoonNow (tm).
On Windows, getaddrinfo is part of the Windows API and as such is
__stdcall, not __cdecl, so check_function_exists fails because the
declaration doesn't match the mangling __stdcall has. Instead, use a
header to include the symbol as declared on the system and use
check_symbol_exists instead.
Tested-By: greatwolf on IRC
