Remove @SystemApi from Compatibility

Bug: 152322291
Bug: 172934376
Test: make

The UI Rendering mainline module is on hold for now, so this does not
need to be @SystemApi. The system can still access it through @hide.

This leaves in place the new Compatibility class (added in
Ie7172fb93364a1e04ab844b8fa64887bf9d8b005), which seems just as good as
the old approach, and we can switch it back to @SystemApi if/when we
restart the module.

Change-Id: I3f6c32603c4eace55ece04936bff6f9336cf6627

core/api/module-lib-current.txt

@@ -42,14 +42,6 @@ package android.content.rollback {
 
 }
 
-package android.graphics {
-
-  public final class Compatibility {
-    method public static void setTargetSdkVersion(int);
-  }
-
-}
-
 package android.media {
 
   public class AudioManager {

graphics/java/android/graphics/Compatibility.java

@@ -16,14 +16,11 @@
 
 package android.graphics;
 
-import android.annotation.SystemApi;
-
 /**
  * Helper class for graphics classes to retrieve the targetSdkVersion, as
  * specified by the app.
  * @hide
  */
-@SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
 public final class Compatibility {
     private Compatibility() {}
 
@@ -34,7 +31,6 @@ public final class Compatibility {
      * application. No other code should call this.
      * @hide
      */
-    @SystemApi(client = SystemApi.Client.MODULE_LIBRARIES)
     public static void setTargetSdkVersion(int targetSdkVersion) {
         sTargetSdkVersion = targetSdkVersion;
         Canvas.setCompatibilityVersion(targetSdkVersion);