Fix warning on 64-bit Windows where a socket isn't an int.

Le sigh for the socket API.

src/syncterm/conn.c

@@ -474,7 +474,7 @@ enum failure_reason {
 	FAILURE_DISCONNECTED
 };
 
-int
+SOCKET
 conn_socket_connect(struct bbslist *bbs)
 {
 	SOCKET           sock = INVALID_SOCKET;

src/syncterm/conn.h

@@ -123,6 +123,6 @@ size_t conn_buf_wait_cond(struct conn_buffer *buf, size_t bcount, unsigned long
 
 #define conn_buf_wait_bytes(buf, count, timeout) conn_buf_wait_cond(buf, count, timeout, 0)
 #define conn_buf_wait_free(buf, count, timeout) conn_buf_wait_cond(buf, count, timeout, 1)
-int conn_socket_connect(struct bbslist *bbs);
+SOCKET conn_socket_connect(struct bbslist *bbs);
 
 #endif // ifndef _CONN_H_