playlist/Song: add "noexcept"

src/playlist/PlaylistSong.cxx

@@ -29,7 +29,7 @@
 #include <string.h>
 
 static void
-merge_song_metadata(DetachedSong &add, const DetachedSong &base)
+merge_song_metadata(DetachedSong &add, const DetachedSong &base) noexcept
 {
 	if (base.GetTag().IsDefined()) {
 		TagBuilder builder(add.GetTag());
@@ -41,7 +41,7 @@ merge_song_metadata(DetachedSong &add, const DetachedSong &base)
 }
 
 static bool
-playlist_check_load_song(DetachedSong &song, const SongLoader &loader)
+playlist_check_load_song(DetachedSong &song, const SongLoader &loader) noexcept
 try {
 	DetachedSong tmp = loader.LoadSong(song.GetURI());
 
@@ -57,7 +57,7 @@ try {
 
 bool
 playlist_check_translate_song(DetachedSong &song, const char *base_uri,
-			      const SongLoader &loader)
+			      const SongLoader &loader) noexcept
 {
 	if (base_uri != nullptr && strcmp(base_uri, ".") == 0)
 		/* PathTraitsUTF8::GetParent() returns "." when there

src/playlist/PlaylistSong.hxx

@@ -31,6 +31,6 @@ class DetachedSong;
  */
 bool
 playlist_check_translate_song(DetachedSong &song, const char *base_uri,
-			      const SongLoader &loader);
+			      const SongLoader &loader) noexcept;
 
 #endif