Implement PSA ITS over files

Implement the PSA ITS API over stdio files.
diff --git a/visualc/VS2010/mbedTLS.vcxproj b/visualc/VS2010/mbedTLS.vcxproj
index aa48c16..08ab37d 100644
--- a/visualc/VS2010/mbedTLS.vcxproj
+++ b/visualc/VS2010/mbedTLS.vcxproj
@@ -304,6 +304,7 @@
     <ClCompile Include="..\..\library\psa_crypto_storage.c" />

     <ClCompile Include="..\..\library\psa_crypto_storage_file.c" />

     <ClCompile Include="..\..\library\psa_crypto_storage_its.c" />

+    <ClCompile Include="..\..\library\psa_its_file.c" />

     <ClCompile Include="..\..\library\ripemd160.c" />

     <ClCompile Include="..\..\library\rsa.c" />

     <ClCompile Include="..\..\library\rsa_internal.c" />