src: reject large raw payload and concat expressions

src: reject large raw payload and concat expressions

The kernel will reject this too, but unfortunately nft may try
to cram the data into the underlying libnftnl expr.

This causes heap corruption or
BUG: nld buffer overflow: want to copy 132, max 64

After:

Error: Concatenation of size 544 exceeds maximum size of 512
udp length . @th,0,512 . @th,512,512 { 47-63 . 0xe373135363130 . 0x33131303735353203 }
                           ^^^^^^^^^

resp. same warning for an over-sized raw expression.

Signed-off-by: Florian Westphal <fw@strlen.de>