meta: Add a #define for memory metadata

docs/gst/gstreamer-sections.txt

@@ -282,6 +282,7 @@ GST_META_TRANSFORM_IS_COPY
 gst_meta_api_type_register
 gst_meta_api_type_has_tag
 GST_META_TAG_MEMORY
+GST_META_TAG_MEMORY_STR
 gst_meta_register
 gst_meta_get_info
 <SUBSECTION Standard>

gst/gstmeta.h

@@ -81,6 +81,14 @@ typedef enum {
  */
 #define GST_META_FLAG_UNSET(meta,flag)         (GST_META_FLAGS (meta) &= ~(flag))
 
+/**
+ * GST_META_TAG_MEMORY_STR:
+ * This metadata stays relevant as long as memory layout is unchanged.
+ *
+ * Since: 1.2
+ */
+#define GST_META_TAG_MEMORY_STR "memory"
+
 /**
  * GstMeta:
  * @flags: extra flags for the metadata
@@ -199,7 +207,7 @@ const GstMetaInfo *  gst_meta_register          (GType api, const gchar *impl,
                                                  GstMetaFreeFunction      free_func,
                                                  GstMetaTransformFunction transform_func);
 const GstMetaInfo *  gst_meta_get_info          (const gchar * impl);
-const gchar* const* gst_meta_api_type_get_tags  (GType api);
+const gchar* const*  gst_meta_api_type_get_tags (GType api);
 
 /* some default tags */
 GST_EXPORT GQuark _gst_meta_tag_memory;

win32/common/libgstreamer.def

@@ -665,6 +665,7 @@ EXPORTS
 	gst_message_type_get_name
 	gst_message_type_get_type
 	gst_message_type_to_quark
+	gst_meta_api_type_get_tags
 	gst_meta_api_type_has_tag
 	gst_meta_api_type_register
 	gst_meta_flags_get_type