Merge changes from topic "signalstrength_ctr"

* changes:
  Make SignalStrength constructor public
  Expose SignalStrength copy constructor

core/api/current.txt

@@ -46095,6 +46095,7 @@ package android.telephony {
   }
 
   public class SignalStrength implements android.os.Parcelable {
+    ctor public SignalStrength(@NonNull android.telephony.SignalStrength);
     method public int describeContents();
     method @Deprecated public int getCdmaDbm();
     method @Deprecated public int getCdmaEcio();

telephony/java/android/telephony/SignalStrength.java

@@ -287,11 +287,9 @@ public class SignalStrength implements Parcelable {
     }
 
     /**
-     * Copy constructors
+     * This constructor is used to create a copy of an existing SignalStrength object.
      *
      * @param s Source SignalStrength
-     *
-     * @hide
      */
     public SignalStrength(@NonNull SignalStrength s) {
         copyFrom(s);