hls muxer: add workaround for bug on latest iPhone iOS

In iPhone iOs 16.1.1, the EXT-X-PRELOAD-HINT file is requested without
the last character, and "partXX.mp4" becomes "partXX.mp"

internal/core/hls_server.go

@@ -285,7 +285,8 @@ func (s *hlsServer) onRequest(ctx *gin.Context) {
 	dir, fname := func() (string, string) {
 		if strings.HasSuffix(pa, ".m3u8") ||
 			strings.HasSuffix(pa, ".ts") ||
-			strings.HasSuffix(pa, ".mp4") {
+			strings.HasSuffix(pa, ".mp4") ||
+			strings.HasSuffix(pa, ".mp") {
 			return gopath.Dir(pa), gopath.Base(pa)
 		}
 		return pa, ""
@@ -297,6 +298,10 @@ func (s *hlsServer) onRequest(ctx *gin.Context) {
 		return
 	}
 
+	if strings.HasSuffix(fname, ".mp") {
+		fname += "4"
+	}
+
 	dir = strings.TrimSuffix(dir, "/")
 
 	hreq := &hlsMuxerRequest{