Fix reading of unitialized memory

Could be reached via few of our lvm2 test cases:

==11501== Invalid read of size 8
==11501==    at 0x49B2E0: _area_length (import-extents.c:204)
==11501==    by 0x49B40C: _read_linear (import-extents.c:222)
==11501==    by 0x49B952: _build_segments (import-extents.c:323)
==11501==    by 0x49B9A0: _build_all_segments (import-extents.c:334)
==11501==    by 0x49BB4C: import_extents (import-extents.c:364)
==11501==    by 0x497655: _format1_vg_read (format1.c:217)
==11501==    by 0x47E43E: _vg_read (metadata.c:2901)

cut from t-vgcvgbackup-usage.sh
--
pvcreate -M1 $(cat DEVICES)
vgcreate -M1 -c n $vg $(cat DEVICES)
lvcreate -l1 -n $lv1 $vg $dev1
--

Idea of the fix is rather defensive - to allocate one extra element
to 'map' array which is then used in _area_length() - where the
loop checks, whether next map entry is continuous.

By placing there always one extra zero entry -
we fix the read of unallocated memory, and we make sure the data would
not make a continous block.

FIXME: there could be a problem if some special broken lvm1 data would be imported.
As the format1 is currently not really used - leave it for future fix
and use this small hotfix for now.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.85 - 
 ===================================
+  Fix reading of unallocated memory in lvm1 format import function.
   Replace several strncmp() calls with id_equal().
   Fix lvmcache_info transfer to orphan_vginfo in _lvmcache_update_vgname().
   Fix -Wold-style-definition gcc warnings.

lib/format1/import-extents.c

@@ -63,8 +63,12 @@ static struct dm_hash_table *_create_lv_maps(struct dm_pool *mem,
 			goto_bad;
 
 		lvm->lv = ll->lv;
+		/*
+		 * Alloc 1 extra element, so the loop in _area_length() and
+		 * _check_stripe() finds the last map member as noncontinuous.
+		 */
 		if (!(lvm->map = dm_pool_zalloc(mem, sizeof(*lvm->map)
-					     * ll->lv->le_count)))
+					     * (ll->lv->le_count + 1))))
 			goto_bad;
 
 		if (!dm_hash_insert(maps, ll->lv->name, lvm))