Rebase: include new commit signing callback

Author: ethomson

LibGit2Sharp/Core/GitRebaseOptions.cs

@@ -17,5 +17,7 @@ internal class GitRebaseOptions
         public GitMergeOpts merge_options = new GitMergeOpts { Version = 1 };
 
         public GitCheckoutOpts checkout_options = new GitCheckoutOpts { version = 1 };
+
+        public NativeMethods.commit_signing_callback signing_callback;
     }
 }

LibGit2Sharp/Core/NativeMethods.cs

@@ -321,6 +321,13 @@ internal static extern unsafe int git_branch_remote_name(
             git_repository* repo,
             [MarshalAs(UnmanagedType.CustomMarshaler, MarshalCookie = UniqueId.UniqueIdentifier, MarshalTypeRef = typeof(StrictUtf8Marshaler))] string canonical_branch_name);
 
+        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+        internal delegate int commit_signing_callback(
+            IntPtr signature,
+            IntPtr signature_field,
+            IntPtr commit_content,
+            IntPtr payload);
+
         [DllImport(libgit2, CallingConvention = CallingConvention.Cdecl)]
         internal static extern unsafe int git_rebase_init(
             out git_rebase* rebase,