#24 feature: drop-in replacement for rpc in glibc 2.14

[arekm]

glibc 2.14 comes with such change:

"* The RPC implementation in libc is obsoleted. Old programs keep working
but new programs cannot be linked with the routines in libc anymore.
Programs in need of RPC functionality must be linked against TI-RPC."

glibc 2.14 removed rpc headers. Thus programs requiring rpc don't build.

Unfortunately libtirpc is not ready for being a drop-in replacement. This feature request is about making libtirpc,
a dropin replacement for glibc rpc on a install level, so:

it should install headers in place where these were in glibc

[arekm]

libtirpc also misses many headers that were in glibc 2.13 and are no longer in glibc 2.14:

rpc/auth_des.h
rpc/auth.h
rpc/auth_unix.h
rpc/clnt.h
rpc/des_crypt.h
rpc/key_prot.h
rpc/pmap_clnt.h
rpc/pmap_prot.h
rpc/pmap_rmt.h
rpc/rpc_des.h
rpc/rpc.h
rpc/rpc_msg.h
rpc/svc_auth.h
rpcsvc/bootparam.h
rpc/svc.h
rpcsvc/nis_callback.h
rpcsvc/nis.h
rpcsvc/nislib.h
rpcsvc/nis_tags.h
rpcsvc/ypclnt.h
rpcsvc/yp.h
rpcsvc/yp_prot.h
rpcsvc/ypupd.h
rpc/types.h
rpc/xdr.h