MT#55283 fix bencode buffer alignment

Make sure data is 64-bit aligned. Fixes alignment issues on certain
32-bit archs (armhf).

Change-Id: I66c1fc20e97c62d3d5e266e874812aed74d295ed
(cherry picked from commit 31375ca349)
(cherry picked from commit 53a08ffe00)

lib/bencode.c

@@ -15,13 +15,11 @@
 
 #define BENCODE_HASH_BUCKETS		31 /* prime numbers work best */
 
-#define BENCODE_ALLOC_ALIGN		8
-
 struct __bencode_buffer_piece {
 	char *tail;
 	size_t left;
 	struct __bencode_buffer_piece *next;
-	char buf[0];
+	char buf[0] __attribute__ ((aligned (BENCODE_ALLOC_ALIGN)));
 };
 struct __bencode_hash {
 	struct bencode_item *buckets[BENCODE_HASH_BUCKETS];

lib/bencode.h

@@ -6,6 +6,8 @@
 
 #include "compat.h"
 
+#define BENCODE_ALLOC_ALIGN 8
+
 struct bencode_buffer;
 enum bencode_type;
 struct bencode_item;
@@ -34,7 +36,7 @@ struct bencode_item {
 	long long int value;	/* when decoding an integer, contains the value; otherwise used internally */
 	bencode_item_t *parent, *child, *last_child, *sibling;
 	bencode_buffer_t *buffer;
-	char __buf[0];
+	char __buf[0] __attribute__ ((aligned (BENCODE_ALLOC_ALIGN)));
 };
 
 struct bencode_buffer {