Hide java.security.Signatue#getCurrentSpi

Internal implementation detail, shouldn't
be public.

Bug: 26689841

(cherry picked from commit 4e559bcbf31a4f60620ed1a7a80e43f51d4dec83)

Change-Id: I86b9a3fdcab8afe580d153fac28ab85606626672
diff --git a/api/current.txt b/api/current.txt
index c6053df..8130c2e 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -54135,7 +54135,6 @@
   public abstract class Signature extends java.security.SignatureSpi {
     ctor protected Signature(java.lang.String);
     method public final java.lang.String getAlgorithm();
-    method public java.security.SignatureSpi getCurrentSpi();
     method public static java.security.Signature getInstance(java.lang.String) throws java.security.NoSuchAlgorithmException;
     method public static java.security.Signature getInstance(java.lang.String, java.lang.String) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException;
     method public static java.security.Signature getInstance(java.lang.String, java.security.Provider) throws java.security.NoSuchAlgorithmException;
diff --git a/api/system-current.txt b/api/system-current.txt
index 2d6e867..242e3b2 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -57222,7 +57222,6 @@
   public abstract class Signature extends java.security.SignatureSpi {
     ctor protected Signature(java.lang.String);
     method public final java.lang.String getAlgorithm();
-    method public java.security.SignatureSpi getCurrentSpi();
     method public static java.security.Signature getInstance(java.lang.String) throws java.security.NoSuchAlgorithmException;
     method public static java.security.Signature getInstance(java.lang.String, java.lang.String) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException;
     method public static java.security.Signature getInstance(java.lang.String, java.security.Provider) throws java.security.NoSuchAlgorithmException;
diff --git a/api/test-current.txt b/api/test-current.txt
index 1f84800..c966086 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -54152,7 +54152,6 @@
   public abstract class Signature extends java.security.SignatureSpi {
     ctor protected Signature(java.lang.String);
     method public final java.lang.String getAlgorithm();
-    method public java.security.SignatureSpi getCurrentSpi();
     method public static java.security.Signature getInstance(java.lang.String) throws java.security.NoSuchAlgorithmException;
     method public static java.security.Signature getInstance(java.lang.String, java.lang.String) throws java.security.NoSuchAlgorithmException, java.security.NoSuchProviderException;
     method public static java.security.Signature getInstance(java.lang.String, java.security.Provider) throws java.security.NoSuchAlgorithmException;