Problem: Several problems found by Coverity Static Analyzer

Solution: The Coverity Static Code Analyzer was used on libzmq code and found
many issues with uninitialized member variables, some redefinition of variables
hidding previous instances of same variable name and a couple of functions
where return values were not checked, even though all other occurrences were
checked (e.g. init_size() return).

src/signaler.cpp

@@ -539,7 +539,8 @@ int zmq::signaler_t::make_fdpair (fd_t *r_, fd_t *w_)
         saved_errno = WSAGetLastError ();
 
     //  We don't need the listening socket anymore. Close it.
-    closesocket (listener);
+    rc = closesocket (listener);
+	wsa_assert(rc != SOCKET_ERROR);
 
     if (sync != NULL) {
         //  Exit the critical section.