fix examine_brief segfault

When performing an "-Ebs -e <metadata type>" we segfault because the
superblock has been freed too early.  We also leak memory for 'ddf' and
'imsm' because, unlike super[01], we do not implicitly free when
->load_super is called on an already loaded supertype.

So, fix up imsm and ddf to match type 0 and 1 ->load_super() semantics,
and update Examine to not free the superblock until all usages have been
exhausted.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Examine.c

@@ -114,10 +114,8 @@ int Examine(mddev_dev_t devlist, int brief, int export, int scan,
 				ap->st = st;
 				arrays = ap;
 				st->ss->getinfo_super(st, &ap->info);
-			} else {
+			} else
 				st->ss->getinfo_super(st, &ap->info);
-				st->ss->free_super(st);
-			}
 			if (!(ap->info.disk.state & (1<<MD_DISK_SYNC)))
 				ap->spares++;
 			d = dl_strdup(devlist->devname);

super-ddf.c

@@ -762,6 +762,9 @@ static int load_ddf_local(int fd, struct ddf_super *super,
 static int load_super_ddf_all(struct supertype *st, int fd,
 			      void **sbp, char *devname, int keep_fd);
 #endif
+
+static void free_super_ddf(struct supertype *st);
+
 static int load_super_ddf(struct supertype *st, int fd,
 			  char *devname)
 {
@@ -798,6 +801,8 @@ static int load_super_ddf(struct supertype *st, int fd,
 		return 1;
 	}
 
+	free_super_ddf(st);
+
 	if (posix_memalign((void**)&super, 512, sizeof(*super))!= 0) {
 		fprintf(stderr, Name ": malloc of %zu failed.\n",
 			sizeof(*super));

super-intel.c

@@ -2196,6 +2196,8 @@ static int load_super_imsm(struct supertype *st, int fd, char *devname)
 		return 0;
 #endif
 
+	free_super_imsm(st);
+
 	super = alloc_super(0);
 	if (!super) {
 		fprintf(stderr,