GWin32WinsockFuncs and other stuff

[John Emmas <johne53 tiscali co uk>]

I just updated from glib-2-42 (git) and tried to build with MSVC but I'm 
suddenly getting tons of compiler errors (particularly relating to 
'ws2funcs').  It seems to get declared at the top of gio/gnetworking.c 
like so:-

       GWin32WinsockFuncs ws2funcs = {0};

but 'GWin32WinsockFuncs' itself doesn't seem to be declared anywhere.  
ws2funcs is also used in other source files too, without being declared 
('gio/ginetaddress.c' and 'gio/gsocket.c').

There's a further problem at line 29 of a newly introduced header file 
(gio/gwin32networking.h):-

        typedef NET_IFINDEX (WINAPI *PFN_IfNameToIndex) (PCSTR);

I'm guessing the compiler doesn't know what 'WINAPI' is (the nearby 
typedefs are all declared with 'WSAAPI').  And other problems too. It's 
unusual to get so many source errors at once like this in a stable 
branch.  It kinda has the feel of some development code that got pushed 
to glib-2-42 by mistake maybe?

John