Revert "Remove Activity Recognition from the Android Code."

This reverts commit e24f1b095b020382f555c7f34f22ff3fb5005f90.

Reason for revert: b/123172409

Change-Id: Ic5863a8e8b36c8c4d8636cc4c004ad9606a3f523
diff --git a/core/jni/Android.bp b/core/jni/Android.bp
index c5dfe6c..be12700 100644
--- a/core/jni/Android.bp
+++ b/core/jni/Android.bp
@@ -186,6 +186,7 @@
         "android_hardware_UsbDevice.cpp",
         "android_hardware_UsbDeviceConnection.cpp",
         "android_hardware_UsbRequest.cpp",
+        "android_hardware_location_ActivityRecognitionHardware.cpp",
         "android_util_FileObserver.cpp",
         "android/opengl/poly_clip.cpp", // TODO: .arm
         "android/opengl/util.cpp",