src: fix discards 'const' qualifier

src: fix discards 'const' qualifier

argv is passed by parse_change_counters_rule and do_parse to parse_rule_range
as a const char. parse_rule_range modifies thepassed in argv, so pass as
non const so that it can be modified without warning.

Fixes:
iptables/xshared.c: In function 'parse_rule_range':
iptables/xshared.c:912:23: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
 912 |         char *colon = strchr(argv, ':'), *buffer;
     |                       ^~~~~~

p is used as the return from strchr(sctp_chunk_names[i].valid_flags)
which is a const char. Declare p as a const char * pointer for use
addressing the warning.

Fixes:
extensions/libxt_sctp.c: In function 'parse_sctp_chunk':
extensions/libxt_sctp.c:211:40: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  211 |                                 if ((p = strchr(sctp_chunk_names[i].valid_flags,
      |                                        ^

next is used as the return from strchr(loop) which is a const char.
Declare next as a const char * pointer for use addressing the warning.

Fixes:
 libxtables/xtables.c: In function 'xtables_ipparse_multiple':
 libxtables/xtables.c:1767:22: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
 1767 |                 next = strchr(loop, ',');
      |                      ^
 libxtables/xtables.c: In function 'xtables_ip6parse_multiple':
 libxtables/xtables.c:2066:22: warning: assignment discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
 2066 |                 next = strchr(loop, ',');
      |                      ^

Signed-off-by: Rudi Heitbaum <rudi@heitbaum.com>
Signed-off-by: Florian Westphal <fw@strlen.de>