client: Don't handle hotkeys while sticky alt is active

In some cases rhev-m changes the hotkey for releasing the mouse grab
to ctrl + alt. This makes it impossible to send ctrl + alt + other-key
to the guest, even when using sticky alt.

What happens is:
-press alt until sticky alt activates
-release alt (but recorded state stays pressed due to sticky alt)
-press ctrl
-hotkey code sees ctrl+alt pressed, releases mouse grab
-mouse grab release code does an unpress all -> end of sticky state.

This patch makes it possible to atleast send ctrl + alt + del (or other key)
using sticky alt. Note: even with this patch it is still a bad idea to
use ctrl + alt as hotkey combi.

client/application.cpp

@@ -1247,10 +1247,12 @@ void Application::on_key_down(RedKey key)
         }
     }
 
-    int command = get_hotkeys_commnad();
-    if (command != APP_CMD_INVALID) {
-        do_command(command);
-        return;
+    if (!_sticky_info.sticky_mode) {
+        int command = get_hotkeys_commnad();
+        if (command != APP_CMD_INVALID) {
+            do_command(command);
+            return;
+        }
     }
 
 #ifdef WIN32