Isolate SpriteIcon into its own file.

This is to isolate differences between internal master and AOSP so that
the open source intern can work on a relatively new project.

It also isolates a divergent piece of code into SpriteIcon.cpp.

Bug: None
Test: Pointer icons in ApiDemos still work.
Change-Id: I1bf8f23411ad7170de2497d6fee0f70b015e9b5f
Merged-In: I1bf8f23411ad7170de2497d6fee0f70b015e9b5f
(cherry picked from commit 7e3457e593f417eb7a5a55d301b3d5f5dd1debdf)
diff --git a/libs/input/Android.bp b/libs/input/Android.bp
index 88d6033..5252cd0 100644
--- a/libs/input/Android.bp
+++ b/libs/input/Android.bp
@@ -17,6 +17,7 @@
     srcs: [
         "PointerController.cpp",
         "SpriteController.cpp",
+        "SpriteIcon.cpp",
     ],
 
     shared_libs: [