added b64.c to the sources neede for grpc_base
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
index 5021cb4..ff0ca35 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
@@ -250,6 +250,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\json\json_writer.c">
       <Filter>src\core\lib\json</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\security\util\b64.c">
+      <Filter>src\core\lib\security\util</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\slice\percent_encoding.c">
       <Filter>src\core\lib\slice</Filter>
     </ClCompile>
@@ -1313,6 +1316,12 @@
     <Filter Include="src\core\lib\json">
       <UniqueIdentifier>{681cdaeb-c47f-8853-d985-bf13c2873947}</UniqueIdentifier>
     </Filter>
+    <Filter Include="src\core\lib\security">
+      <UniqueIdentifier>{02c849c5-66eb-e42f-c9f7-2cf7cc9db06a}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="src\core\lib\security\util">
+      <UniqueIdentifier>{c22aef1f-8b7b-6b5c-9e22-321b11f6352d}</UniqueIdentifier>
+    </Filter>
     <Filter Include="src\core\lib\slice">
       <UniqueIdentifier>{74c81ab7-e329-a362-3890-4c41b90f0511}</UniqueIdentifier>
     </Filter>