Eliminate hw.keyboards system properties.

Stop using system properties to publish information about
the key character map path.  Instead, we can retrieve it
on demand by asking the window manager.

It was possible to exhaust the supply of system properties
when repeatedly adding and removing input devices.

Bug: 5532806
Change-Id: Idd361a24ad7db2edc185c8546db7fb05f9c28669
diff --git a/include/ui/Input.h b/include/ui/Input.h
index 438a1a0..c2cbe1d 100644
--- a/include/ui/Input.h
+++ b/include/ui/Input.h
@@ -826,6 +826,9 @@
     inline void setKeyboardType(int32_t keyboardType) { mKeyboardType = keyboardType; }
     inline int32_t getKeyboardType() const { return mKeyboardType; }
 
+    inline void setKeyCharacterMapFile(const String8& value) { mKeyCharacterMapFile = value; }
+    inline const String8& getKeyCharacterMapFile() const { return mKeyCharacterMapFile; }
+
     inline const Vector<MotionRange>& getMotionRanges() const {
         return mMotionRanges;
     }
@@ -835,6 +838,7 @@
     String8 mName;
     uint32_t mSources;
     int32_t mKeyboardType;
+    String8 mKeyCharacterMapFile;
 
     Vector<MotionRange> mMotionRanges;
 };