Move KeyCharacterMap from RefBase to shared_ptr.

Move KeyCharacterMap from RefBase and make it shared_ptr in EventHub
device when loaded from file.
A shared_ptr of KeyCharacterMap is returned by EventHub getKeyCharacterMap
to be shared in InputdeviceInfo.
Remove extra KeyCharacterMap in EventHub to save memory sapce.

Bug: 160010896
Test: atest inputflinger, atest libinput_tests

Change-Id: Ibb317ea0684e6af6e7a6d808f816fc4a05c7b421
diff --git a/services/inputflinger/reader/InputDevice.cpp b/services/inputflinger/reader/InputDevice.cpp
index 4960779..b224476 100644
--- a/services/inputflinger/reader/InputDevice.cpp
+++ b/services/inputflinger/reader/InputDevice.cpp
@@ -240,7 +240,7 @@
 
         if (!changes || (changes & InputReaderConfiguration::CHANGE_KEYBOARD_LAYOUTS)) {
             if (!mClasses.test(InputDeviceClass::VIRTUAL)) {
-                sp<KeyCharacterMap> keyboardLayout =
+                std::shared_ptr<KeyCharacterMap> keyboardLayout =
                         mContext->getPolicy()->getKeyboardLayoutOverlay(mIdentifier);
                 bool shouldBumpGeneration = false;
                 for_each_subdevice(