Remove unused imports from frameworks/base.

core/java/android/accounts/AccountAuthenticatorActivity.java

core/java/android/accounts/AccountManagerFuture.java

.../android/accounts/GrantCredentialsPermissionActivity.java

core/java/android/annotation/IntDef.java

core/java/android/annotation/StringDef.java

core/java/android/app/AlertDialog.java

core/java/android/app/ApplicationErrorReport.java

core/java/android/app/ApplicationPackageManager.java

core/java/android/app/Dialog.java

core/java/android/app/ExpandableListActivity.java

core/java/android/app/ResultInfo.java

core/java/android/app/SearchManager.java

core/java/android/app/SharedPreferencesImpl.java

core/java/android/app/WallpaperManager.java

core/java/android/app/backup/FullBackup.java

...ava/android/app/backup/SharedPreferencesBackupHelper.java

core/java/android/appwidget/AppWidgetHost.java

core/java/android/appwidget/AppWidgetManager.java

core/java/android/bluetooth/BluetoothAdapter.java

core/java/android/bluetooth/BluetoothDevice.java