Fixed iterator when erasing from inprocs multimap

src/socket_base.cpp

@@ -1011,7 +1011,8 @@ void zmq::socket_base_t::terminated (pipe_t *pipe_)
     xterminated (pipe_);
 
     // Remove pipe from inproc pipes
-    for (inprocs_t::iterator it = inprocs.begin(); it != inprocs.end(); ++it) {
+    inprocs_t::iterator it = inprocs.begin();
+    while (it != inprocs.end()) {
         if (it->second == pipe_) {
             inprocs.erase(it++);
         } else {