MFC r319369:

* limit size of buffers to RPC_MAXDATASIZE
* don't leak memory
* be more picky about bad parameters

From:

https://raw.githubusercontent.com/guidovranken/rpcbomb/master/libtirpc_patch.txt
https://github.com/guidovranken/rpcbomb/blob/master/rpcbind_patch.txt

via NetBSD.

MFC r301754,r301769:

r301754 (by pfg):

libc/rpc: Make use of some xdr_* macros.

xdr_rpcprog and xdr_rpcvers were broken in older versions of FreeBSD
but were fixed in r296394. Give them some use hoping they help make
the code somewhat more readable.

r301769 (by pfg):

libc/rpc: Make use of some xdr_* macros. (part 2)

xdr_rpcproc, xdr_rpcprog and xdr_rpcvers were broken in older
versions of FreeBSD but fixed in r296394. Give them some use
hoping they help make the code somewhat more readable.

MFC r288113:
r288113 (by rodrigc):

Use ANSI C prototypes. Eliminates -Wold-style-definition warnings.

MFC r258578, r258580, r258581 (by hrs):
Replace Sun RPC license in TI-RPC library with a 3-clause BSD license
with the explicit permissions.

MFC r258578, r258580, r258581 (by hrs):
Replace Sun RPC license in TI-RPC library with a 3-clause BSD license
with the explicit permissions.