evaluate: do not crash on runaway number of concatenation components

evaluate: do not crash on runaway number of concatenation components

Display error message in case user specifies more data components than
those defined by the concatenation of selectors.

 # cat example.nft
 table ip x {
        chain y {
                type filter hook prerouting priority 0; policy drop;
                ip saddr . meta mark { 1.2.3.4 . 0x00000100 . 1.2.3.6-1.2.3.8 } accept
        }
 }
 # nft -f example.nft
 example.nft:4:3-22: Error: too many concatenation components
                ip saddr . meta mark { 1.2.3.4 . 0x00000100 . 1.2.3.6-1.2.3.8 } accept
                ~~~~~~~~~~~~~~~~~~~~   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Without this patch, nft crashes:

==464771==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60d000000418 at pc 0x7fbc17513aa5 bp 0x7ffc73d33c90 sp 0x7ffc73d33c88
READ of size 8 at 0x60d000000418 thread T0
    #0 0x7fbc17513aa4 in expr_evaluate_concat /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:1348
    #1 0x7fbc1752a9da in expr_evaluate /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:2476
    #2 0x7fbc175175e2 in expr_evaluate_set_elem /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:1504
    #3 0x7fbc1752aa22 in expr_evaluate /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:2482
    #4 0x7fbc17512cb5 in list_member_evaluate /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:1310
    #5 0x7fbc17518ca0 in expr_evaluate_set /home/pablo/devel/scm/git-netfilter/nftables/src/evaluate.c:1590
    [...]

Fixes: 64bb3f43bb96 ("src: allow to use typeof of raw expressions in set declaration")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>