TagNames: make tag_item_names const

src/tag/TagNames.c

@@ -20,7 +20,7 @@
 #include "config.h"
 #include "TagType.h"
 
-const char *tag_item_names[TAG_NUM_OF_ITEM_TYPES] = {
+const char *const tag_item_names[TAG_NUM_OF_ITEM_TYPES] = {
 	[TAG_ARTIST] = "Artist",
 	[TAG_ARTIST_SORT] = "ArtistSort",
 	[TAG_ALBUM] = "Album",

src/tag/TagType.h

@@ -51,6 +51,6 @@ enum tag_type {
  * An array of strings, which map the #tag_type to its machine
  * readable name (specific to the MPD protocol).
  */
-extern const char *tag_item_names[];
+extern const char *const tag_item_names[];
 
 #endif