Sends signal on data()->seq_num

This always should have been there. I just didn't understand how the
signalling worked.

Bug: 80486368
Bug: 80104636
Test: local boot and hammer with adb connect commands
Change-Id: Ic8b902059b2a2ff15959146765c1b96ba2cd0567
diff --git a/common/vsoc/lib/socket_forward_region_view.cpp b/common/vsoc/lib/socket_forward_region_view.cpp
index 0282fd6..5c9c281 100644
--- a/common/vsoc/lib/socket_forward_region_view.cpp
+++ b/common/vsoc/lib/socket_forward_region_view.cpp
@@ -227,6 +227,7 @@
         LOG(DEBUG) << "acquired queue " << id
                    << ". current seq_num: " << data()->seq_num;
         ++data()->seq_num;
+        SendSignal(layout::Sides::Peer, &data()->seq_num);
         return id;
       }
       ++id;