*: add explicit

src/playlist/plugins/CuePlaylistPlugin.cxx

@@ -28,7 +28,7 @@ class CuePlaylist final : public SongEnumerator {
 	CueParser parser;
 
  public:
-	CuePlaylist(InputStreamPtr &&is)
+	explicit CuePlaylist(InputStreamPtr &&is)
 		:tis(std::move(is)) {
 	}
 

src/playlist/plugins/ExtM3uPlaylistPlugin.cxx

@@ -35,7 +35,7 @@ class ExtM3uPlaylist final : public SongEnumerator {
 	TextInputStream tis;
 
 public:
-	ExtM3uPlaylist(InputStreamPtr &&is)
+	explicit ExtM3uPlaylist(InputStreamPtr &&is)
 		:tis(std::move(is)) {
 	}
 

src/playlist/plugins/M3uPlaylistPlugin.cxx

@@ -28,7 +28,7 @@ class M3uPlaylist final : public SongEnumerator {
 	TextInputStream tis;
 
 public:
-	M3uPlaylist(InputStreamPtr &&is)
+	explicit M3uPlaylist(InputStreamPtr &&is)
 		:tis(std::move(is)) {
 	}