qapi: rename BlockDirtyBitmapMergeSource to BlockDirtyBitmapOrStr

Rename the type to be reused. Old name is "what is it for". To be
natively reused for other needs, let's name it exactly "what is it".

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Message-Id: <20220314213226.362217-2-v.sementsov-og@mail.ru>
[eblake: Adjust S-o-b to Vladimir's new email, with permission]
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c
index 4c84134..4cf4d24 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1623,16 +1623,16 @@
                                   const char *src_node, const char *src_name,
                                   Error **errp)
 {
-    BlockDirtyBitmapMergeSource *merge_src;
-    BlockDirtyBitmapMergeSourceList *list = NULL;
+    BlockDirtyBitmapOrStr *merge_src;
+    BlockDirtyBitmapOrStrList *list = NULL;
 
-    merge_src = g_new0(BlockDirtyBitmapMergeSource, 1);
+    merge_src = g_new0(BlockDirtyBitmapOrStr, 1);
     merge_src->type = QTYPE_QDICT;
     merge_src->u.external.node = g_strdup(src_node);
     merge_src->u.external.name = g_strdup(src_name);
     QAPI_LIST_PREPEND(list, merge_src);
     qmp_block_dirty_bitmap_merge(dst_node, dst_name, list, errp);
-    qapi_free_BlockDirtyBitmapMergeSourceList(list);
+    qapi_free_BlockDirtyBitmapOrStrList(list);
 }
 
 enum ImgConvertBlockStatus {