[PATCH] examples: compilation fix for GCC-12

[Amit Prakash Shukla]

GCC-12 warns when a pointer of type union points to an array of same
defined size, as union internally gets paded with pad bytes.

../examples/common/neon/port_group.h:42:21: error: array subscript
	'union <anonymous>[0]' is partly outside array bounds of
	'uint16_t[5]' {aka 'short unsigned int[5]'}
	[-Werror=array-bounds]
   42 |                 pnum->u64 = gptbl[v].pnum;
      |                     ^~
../examples/common/neon/port_group.h:21:23: note: object 'pn' of
	size [0, 10]
   21 | port_groupx4(uint16_t pn[FWDSTEP + 1], uint16_t *lp, uint16x8_t dp1
      |              ~~~~~~~~~^~~~~~~~~~~~~~~
../examples/common/neon/port_group.h:43:21: error: array subscript
	'union <anonymous>[0]' is partly outside array bounds of
	'uint16_t[5]' {aka 'short unsigned int[5]'} [-Werror=array-bounds]
   43 |                 pnum->u16[FWDSTEP] = 1;
      |                     ^~

Fixes: bdfc3816fbfc ("examples: common packet group functionality")
Cc: stable at dpdk.org

Signed-off-by: Amit Prakash Shukla <amitprakashs at marvell.com>
---
 examples/common/neon/port_group.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/common/neon/port_group.h b/examples/common/neon/port_group.h
index 82c6ed6d73..97da604583 100644
--- a/examples/common/neon/port_group.h
+++ b/examples/common/neon/port_group.h
@@ -24,7 +24,7 @@ port_groupx4(uint16_t pn[FWDSTEP + 1], uint16_t *lp, uint16x8_t dp1,
 	union {
 		uint16_t u16[FWDSTEP + 1];
 		uint64_t u64;
-	} *pnum = (void *)pn;
+	} __attribute__((__packed__)) *pnum = (void *)pn;
 
 	uint16x8_t mask = {1, 2, 4, 8, 0, 0, 0, 0};
 	int32_t v;
-- 
2.25.1