Use the new modules stuff to load dynrpc modules. Basically this means:

Use the new modules stuff to load dynrpc modules. Basically this means:
- calling the initialization function in the module init_module() instead of rpc_pipe_init()
- calling smb_load_module() to do the dlopen(), dlsym() and init_module() calls

I'll merge this to 3.0, together with the smb_load_module() function.

Discussed with Anthony.
(This used to be commit 3757ed8df06ca2b306bef336bdb9c7671f5e6a65)