Allow extra keyguard logs to be enabled via adb

To enable extra logs:
adb shell setprop log.tag.Keyguard DEBUG && adb shell am crash com.android.systemui

Test: manually enable logs, check they show in logcat
Bug: 212835832
Change-Id: I29bb0ffefd57d577b5abe942e227eb2b5baeab4e
(cherry picked from commit 382c4e80a7)
Merged-In:I29bb0ffefd57d577b5abe942e227eb2b5baeab4e

packages/SystemUI/src/com/android/keyguard/KeyguardConstants.java

@@ -16,6 +16,8 @@
 
 package com.android.keyguard;
 
+import android.util.Log;
+
 /**
  * Defines constants for the Keyguard.
  */
@@ -25,7 +27,7 @@ public class KeyguardConstants {
      * Turns on debugging information for the whole Keyguard. This is very verbose and should only
      * be used temporarily for debugging.
      */
-    public static final boolean DEBUG = false;
+    public static final boolean DEBUG = Log.isLoggable("Keyguard", Log.DEBUG);
     public static final boolean DEBUG_SIM_STATES = true;
     public static final boolean DEBUG_BIOMETRIC_WAKELOCK = true;
 }