Fix customEvent handlers to chain up to their parent.

The clang-tidy "bugprone parent virtual call" checker pointed out a
couple of places where customEvent handlers either don't call up to
their parent, or skip the parent and call up to the grandparent.  Fix
these so that they all call from child to parent.

https://clang.llvm.org/extra/clang-tidy/checks/bugprone-parent-virtual-call.html

mythplugins/mythzoneminder/mythzoneminder/zmliveplayer.cpp

@@ -297,6 +297,7 @@ void ZMLivePlayer::customEvent(QEvent *event)
             }
         }
     }
+    MythUIType::customEvent(event);
 }
 
 void ZMLivePlayer::changeView(void)

mythplugins/mythzoneminder/mythzoneminder/zmminiplayer.cpp

@@ -105,9 +105,7 @@ void ZMMiniPlayer::customEvent (QEvent* event)
         }
     }
 
-    // Parent MythUIType handler always returns false. (Shouldn't it
-    // call up?)  Continue to call QObject as before.
-    QObject::customEvent(event);
+    ZMLivePlayer::customEvent(event);
 }
 
 bool ZMMiniPlayer::keyPressEvent(QKeyEvent *event)

mythtv/libs/libmythui/mythuitype.cpp

@@ -974,8 +974,9 @@ bool MythUIType::keyPressEvent(QKeyEvent * /*event*/)
 }
 
 
-void MythUIType::customEvent(QEvent * /*event*/)
+void MythUIType::customEvent(QEvent *event)
 {
+    QObject::customEvent(event);
 }
 
 /** \brief Mouse click/movement handler, receives mouse gesture events from the