xdrfile broken with native rpc/xdr

[ksebaz]

It seems the configure of xdrfile is broken on systems with native rpc/xdr. An easy solution would be to simply remove that feature-block from the configure.ac and use the internal xdr-definitions.

[ksebaz]

An easy solution would be to simply remove that feature-block from the configure.ac and use the internal xdr-definitions.

see #57