Remove sunrpc compatibility

Remove sunrpc compatibility

Remove sunrpc compatibility from rxgen. It's not tested, and
rpcgen is available from other sources. This will allow changes to be
made to rxgen without worrying about their impact on rpcgen compatibility.

Removals consist of the -l, -m, and -s switches, the source files
rpc_clntout.c and rpc_svcout.c, and the scan tokens 'program' and
'version'. The -R switch ('R compatibility') is also removed, as it's
a noop.

Change-Id: I960fac14faf072d221b8cb166e9388ab4accfa26
Reviewed-on: http://gerrit.openafs.org/10258
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>