slice2cs bug when using a System module

Hi there,

I defined a slice file, where an interface is defined inside a System namespace/module. The created .cs file can't be compiled by Visual Studio because of naming conflicts. The error occurs in the InterfaceNameDelD_ section of the .cs file and at the end of each function interface function:

catch(System.Exception ex__)
{
    IceInternal.LocalExceptionWrapper.throwWrapper(ex__);
}

I've seen that all other System references are prefixed with _ in the generated file, this seems to be missing here. With the manual fix, it works just fine.