[PATCH] libiptc.c: pragma disable a gcc compiler warning

["Maciej Żenczykowski" <zenczykowski@gmail.com>]

From: Maciej Żenczykowski <maze@google.com>

Fixes:
  In file included from libip4tc.c:113:
  In function ‘iptcc_compile_chain’,
      inlined from ‘iptcc_compile_table’ at libiptc.c:1246:13,
      inlined from ‘iptc_commit’ at libiptc.c:2575:8,
      inlined from ‘iptc_commit’ at libiptc.c:2513:1:
  libiptc.c:1172:2: warning: writing 16 bytes into a region of size 0 [-Wstringop-overflow=]
   1172 |  memcpy(&foot->e.counters, &c->counters, sizeof(STRUCT_COUNTERS));
        |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  In file included from ../include/libiptc/libiptc.h:12,
                   from libip4tc.c:29:
  libiptc.c: In function ‘iptc_commit’:
  ../include/linux/netfilter_ipv4/ip_tables.h:202:19: note: at offset 0 to object ‘entries’ with size 0 declared here
    202 |  struct ipt_entry entries[0];
        |                   ^~~~~~~

Which was found via compilation on Fedora 32.

Test: builds without warnings
Signed-off-by: Maciej Żenczykowski <maze@google.com>
---
 libiptc/libiptc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libiptc/libiptc.c b/libiptc/libiptc.c
index 58882015..1a92b267 100644
--- a/libiptc/libiptc.c
+++ b/libiptc/libiptc.c
@@ -1169,7 +1169,10 @@ static int iptcc_compile_chain(struct xtc_handle *h, STRUCT_REPLACE *repl, struc
 	else
 		foot->target.verdict = RETURN;
 	/* set policy-counters */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
 	memcpy(&foot->e.counters, &c->counters, sizeof(STRUCT_COUNTERS));
+#pragma GCC diagnostic pop
 
 	return 0;
 }
-- 
2.26.2.645.ge9eca65c58-goog