TagString: remove ISO-Latin-1 fallback

MPD handles all strings in UTF-8 internally.  Those decoders which
read Latin-1 tags are supposed to implement the conversion, instead of
passing Latin-1 to TagBuilder::AddItem().  FixTagString() is simply
the wrong place to do that, and hard-coding Latin-1 is kind of
arbitrary.

NEWS

@@ -69,6 +69,7 @@ ver 0.19 (not yet released)
   - allow playlist directory without music directory
   - use XDG to auto-detect "music_directory" and "db_file"
 * add tags "AlbumSort", "MUSICBRAINZ_RELEASETRACKID"
+* disable global Latin-1 fallback for tag values
 * new resampler option using libsoxr
 * ARM NEON optimizations
 * install systemd unit for socket activation

src/tag/TagString.cxx

@@ -52,8 +52,6 @@ static char *
 fix_utf8(const char *str, size_t length)
 {
 	const gchar *end;
-	char *temp;
-	gsize written;
 
 	assert(str != nullptr);
 
@@ -61,18 +59,7 @@ fix_utf8(const char *str, size_t length)
 	if (g_utf8_validate(str, length, &end))
 		return nullptr;
 
-	/* no, it's not - try to import it from ISO-Latin-1 */
-	temp = g_convert(str, length, "utf-8", "iso-8859-1",
-			 nullptr, &written, nullptr);
-	if (temp != nullptr) {
-		/* success! */
-		char *p = xstrdup(temp);
-		g_free(temp);
-		return p;
-	}
-
-	/* no, still broken - there's no medication, just patch
-	   invalid sequences */
+	/* no, broken - patch invalid sequences */
 	return patch_utf8(str, length, end);
 }