avcodec/srtenc, webvttenc: Use av_printf_format

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/srtenc.c

@@ -41,10 +41,7 @@ typedef struct {
 } SRTContext;
 
 
-#ifdef __GNUC__
+static av_printf_format(2, 3) void srt_print(SRTContext *s, const char *str, ...)
-__attribute__ ((__format__ (__printf__, 2, 3)))
-#endif
-static void srt_print(SRTContext *s, const char *str, ...)
 {
     va_list vargs;
     va_start(vargs, str);

libavcodec/webvttenc.c

@@ -38,10 +38,7 @@ typedef struct {
     int stack_ptr;
 } WebVTTContext;
 
-#ifdef __GNUC__
+static av_printf_format(2, 3) void webvtt_print(WebVTTContext *s, const char *str, ...)
-__attribute__ ((__format__ (__printf__, 2, 3)))
-#endif
-static void webvtt_print(WebVTTContext *s, const char *str, ...)
 {
     va_list vargs;
     va_start(vargs, str);