rxgen: Tidy up server side freeing

rxgen: Tidy up server side freeing

The way in which rxgen handles freeing of objects allocated by the RPC
stub has evolved over the years. Originally, there appears to have been
a "somefrees" parameter which was used to track whether objects required
freeing or not. However, this parameter has fallen in to disuse, as
support for typedefs and unions were added, and which parameters
require freed is now tracked within the description structures
themselves. So, get rid of somefrees, as it is now just confusing.

The generated code to free a set of RPC arguments currently looks
something like:

fail:
        z_xdrs->x_op = XDR_FREE;
        if (!xdr_string(z_xdrs, &Name, AFSNAMEMAX)) goto fail1;
        if (!xdr_string(z_xdrs, &OfflineMsg, AFSOPAQUEMAX)) goto fail1;
        if (!xdr_string(z_xdrs, &Motd, AFSOPAQUEMAX)) goto fail1;
        if (rx_enable_stats) {
            rx_RecordCallStatistics(z_call, RXAFS_STATINDEX,
                19, RXAFS_NO_OF_STAT_FUNCS, 0);
        }

        return z_result;
fail1:
        if (rx_enable_stats) {
            rx_RecordCallStatistics(z_call, RXAFS_STATINDEX,
                19, RXAFS_NO_OF_STAT_FUNCS, 0);
        }

        return RXGEN_SS_XDRFREE;

Which isn't very efficient, or easy to modify. So, change the code
generator to produce code that looks like:

fail:
        z_xdrs->x_op = XDR_FREE;
        if ((!xdr_string(z_xdrs, &Name, AFSNAMEMAX))
            || (!xdr_string(z_xdrs, &OfflineMsg, AFSOPAQUEMAX))
            || (!xdr_string(z_xdrs, &Motd, AFSOPAQUEMAX)))
                z_result = RXGEN_SS_XDRFREE;

        if (rx_enable_stats) {
            rx_RecordCallStatistics(z_call, RXAFS_STATINDEX,
                19, RXAFS_NO_OF_STAT_FUNCS, 0);
        }

        return z_result;

This does the same thing, but is easier to read and is more consistent
with the way that we structure marshalling and unmarshalling.

Change-Id: I8b56f320c05c5d4270daf409d57514cbe8d076f5
Reviewed-on: http://gerrit.openafs.org/7005
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>