widl: Use ULONG instead of unsigned long when generating declarations for *_UserFree() functions. This is needed for Win64 compatibility.

widl: Use ULONG instead of unsigned long when generating declarations for *_UserUnMarshal() functions. This is needed for Win64 compatibility.

widl: Use ULONG instead of unsigned long when generating declarations for *_UserMarshal() functions. This is needed for Win64 compatibility.

widl: Use ULONG instead of unsigned long when generating declarations for *_UserSize() functions. This is needed for Win64 compatibility.

so replace it with some more appropriate endpoint error codes.

rpcrt4: Open the endpoint from the caller of RpcServerUseProtseq* instead of the protseq server thread.

This allows errors to be returned to the caller and to create more than 
one connection for an endpoint.

msi: Use disk_prompt from the media_info structure instead of passing an extra parameter to msi_change_media.

secur32: Use a helper function for creating the signature as this simplifies implementing NTLM2 signing a lot.