Ensure that smp_object always are a multiple of 8 bytes.

bin/varnishd/storage/storage_persistent.h

@@ -145,6 +145,7 @@ struct smp_segptr {
 struct smp_object {
 	uint8_t			hash[32];	/* really: DIGEST_LEN */
 	struct exp		exp;
+	uint32_t		__filler__;	/* -> align/8 on 32bit */
 	double			ban;
 	uint64_t		ptr;		/* rel to silo */
 };

bin/varnishd/storage/storage_persistent_mgt.c

@@ -136,6 +136,10 @@ smp_mgt_init(struct stevedore *parent, int ac, char * const *av)
 	ASSERT_MGT();
 
 	AZ(av[ac]);
+
+	/* Necessary alignment. See also smp_object::__filler__ */
+	assert(sizeof(struct smp_object) % 8 == 0);
+
 #define SIZOF(foo)       fprintf(stderr, \
     "sizeof(%s) = %zu = 0x%zx\n", #foo, sizeof(foo), sizeof(foo));
 	SIZOF(struct smp_ident);