Proper type for variables and function arguments

The actual optval argument type is DWORD (boolean) for the SOL_SOCKET
socket option SO_REUSEADDR:
  https://docs.microsoft.com/windows/win32/winsock/sol-socket-socket-options

The type of the optlen argument of setsockopt() is "int":
  https://docs.microsoft.com/windows/win32/api/winsock/nf-winsock-setsockopt#syntax

The type of the namelen argument of getsockname() is "int *":
  https://docs.microsoft.com/windows/win32/api/winsock/nf-winsock-getsockname#syntax

After these changes, socklen_t is not used anymore. Therefore we can
revert from <w2stcpip.h> to <winsock2.h>.

Author: DimitriPapadopoulos

dummy_headers/windows.h

@@ -16,13 +16,12 @@ struct sockaddr_in {
     unsigned short sin_port;
 };
 struct sockaddr { int dummy; };
-typedef unsigned socklen_t;
 #define SOL_SOCKET 66
 #define SO_REUSEADDR 77
 #define INADDR_LOOPBACK 88
 extern int setsockopt(SOCKET, int, int, char*, unsigned);
 extern int bind(SOCKET, struct sockaddr*, unsigned);
-extern int getsockname(SOCKET, struct sockaddr*, socklen_t*);
+extern int getsockname(SOCKET, struct sockaddr*, int*);
 extern int listen(SOCKET, int);
 extern SOCKET WSASocket(int, int, int, void*, int, int);
 extern int connect(SOCKET, struct sockaddr*, unsigned);

dummy_headers/ws2tcpip.h renamed to dummy_headers/winsock2.h

@@ -51,7 +51,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <string.h>
 
 #ifdef WIN32
-# include <ws2tcpip.h>  /* socklen_t, et al (MSVC20xx) */
+# include <winsock2.h>
 # include <windows.h>
 # include <io.h>
 #else
@@ -77,10 +77,10 @@ int dumb_socketpair(SOCKET socks[2], int make_overlapped)
        struct sockaddr addr;
     } a;
     SOCKET listener;
-    int e;
-    socklen_t addrlen = sizeof(a.inaddr);
+    int addrlen = (int) sizeof(a.inaddr);
     DWORD flags = (make_overlapped ? WSA_FLAG_OVERLAPPED : 0);
-    int reuse = 1;
+    DWORD reuse = 1;
+    int e;
 
     if (socks == 0) {
       WSASetLastError(WSAEINVAL);
@@ -99,7 +99,7 @@ int dumb_socketpair(SOCKET socks[2], int make_overlapped)
 
     for (;;) {
         if (setsockopt(listener, SOL_SOCKET, SO_REUSEADDR,
-               (char*) &reuse, (socklen_t) sizeof(reuse)) == SOCKET_ERROR)
+               (const char*) &reuse, (int) sizeof(reuse)) == SOCKET_ERROR)
             break;
         if  (bind(listener, &a.addr, sizeof(a.inaddr)) == SOCKET_ERROR)
             break;