avcodec/libzvbi-teletextdec: change new lines to \n in ASS header

Fixes remaining \r\n is ASS header after 57c5450.

Fixes AVERROR_BUG error during init as this decoder expected `\r\n` in
default ASS header. strstr(..., "\r\n[Events]\r\n") failed after changes
in 57c5450.

Fixes ticket #11545.

Fixes: 57c5450
Signed-off-by: Kacper Michajłow <[email protected]>
Signed-off-by: Marton Balint <[email protected]>

Author: kasper93

libavcodec/libzvbi-teletextdec.c

@@ -91,7 +91,7 @@ static int my_ass_subtitle_header(AVCodecContext *avctx)
     if (ret < 0)
         return ret;
 
-    event_pos = strstr(avctx->subtitle_header, "\r\n[Events]\r\n");
+    event_pos = strstr(avctx->subtitle_header, "\n[Events]\n");
     if (!event_pos)
         return AVERROR_BUG;
 
@@ -106,7 +106,7 @@ static int my_ass_subtitle_header(AVCodecContext *avctx)
         "0,0,"                 /* Spacing, Angle */
         "3,0.1,0,"             /* BorderStyle, Outline, Shadow */
         "5,1,1,1,"             /* Alignment, Margin[LRV] */
-        "0\r\n"                /* Encoding */
+        "0\n"                  /* Encoding */
         "Style: "
         "Subtitle,"            /* Name */
         "Monospace,16,"        /* Font{name,size} */
@@ -116,7 +116,7 @@ static int my_ass_subtitle_header(AVCodecContext *avctx)
         "0,0,"                 /* Spacing, Angle */
         "1,1,1,"               /* BorderStyle, Outline, Shadow */
         "8,48,48,20,"          /* Alignment, Margin[LRV] */
-        "0\r\n"                /* Encoding */
+        "0\n"                  /* Encoding */
         , event_pos);
 
     if (!new_header)