[REG: 5.3-5.6] Many shortcuts don't work on OSX when Japanese input sources are used

To reproduce:
1) Add the language support as on the picture. But you can use a standard US/EU keyboard.
2) Select the Romaji language as active input
3) Run the attached sample.

It won't work because of step #2
Note: this worked in Qt 5.3.0

The root of the problem lies in QCocoaKeyMapper::updateKeyMap
(qcocoakeymapper.mm)

UCKeyTranslate returns "error" and qt_mac_get_key is called with "unicodeKey" as argument. The problem is that this value is not an unicode value but a Qt virtual key code, and this clashes with the table lookup 'qt_mac_keyboard_symbols'.

To solve the problem, I had to do several things:

• in qt_mac_get_key, check qt_mac_keyvkey_symbols before the rest, if UCKeyTranslate failed.
• Complement the table qt_mac_keyvkey_symbols with:

      { kVK_Delete, QT_MAC_MAP_ENUM(Qt::Key_Backspace) },
      { kVK_ForwardDelete, QT_MAC_MAP_ENUM(Qt::Key_Delete) },
      { kVK_Home, QT_MAC_MAP_ENUM(Qt::Key_Home) },
      { kVK_End, QT_MAC_MAP_ENUM(Qt::Key_End) },
      { kVK_F17, QT_MAC_MAP_ENUM(Qt::Key_F17) },
      { kVK_F18, QT_MAC_MAP_ENUM(Qt::Key_F18) },
      { kVK_F19, QT_MAC_MAP_ENUM(Qt::Key_F19) },
      { kVK_F20, QT_MAC_MAP_ENUM(Qt::Key_F20) },