rbd: use ListChildrenAttributes() instead of ListChildren()

This commit modifies listSnapAndChildren() to make use of
ListChildrenAttributes() instead of ListChildren() which
allows us to filter out images in trash.
This commit also order the alive images so that temp clone
images are followed by images backing volume snapshots so
that temp clone images are flattened first.

Signed-off-by: Rakshith R <rar@redhat.com>

vendor/github.com/ceph/go-ceph/rbd/encryption_load2.go

@@ -81,25 +81,22 @@ func (image *Image) EncryptionLoad2(opts []EncryptionOptions) error {
 	}
 
 	length := len(opts)
-	cspecs := (*C.rbd_encryption_spec_t)(C.malloc(
-		C.size_t(C.sizeof_rbd_encryption_spec_t * length)))
-	specs := unsafe.Slice(cspecs, length)
+	cspecs := make([]C.rbd_encryption_spec_t, length)
 	freeFuncs := make([]func(), length)
 
 	for idx, option := range opts {
-		f := option.(encryptionOptions2).writeEncryptionSpec(&specs[idx])
+		f := option.(encryptionOptions2).writeEncryptionSpec(&cspecs[idx])
 		freeFuncs[idx] = f
 	}
 	defer func() {
 		for _, f := range freeFuncs {
 			f()
 		}
-		C.free(unsafe.Pointer(cspecs))
 	}()
 
 	ret := C.rbd_encryption_load2(
 		image.image,
-		cspecs,
+		(*C.rbd_encryption_spec_t)(unsafe.Pointer(&cspecs[0])),
 		C.size_t(length))
 	return getError(ret)
 }