Add missing prototype for ff_is_hwaccel_pix_fmt().

patch by Gwenole Beauchesne, gbeauchesne,splitted-desktop,com

Originally committed as revision 17593 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/internal.h

@@ -47,6 +47,11 @@ void ff_log_missing_feature(void *avc, const char *feature, int want_sample);
  */
 void ff_log_ask_for_sample(void *avc, const char *msg);
 
+/**
+ * Determines whether \p pix_fmt is a hardware accelerated format.
+ */
+int ff_is_hwaccel_pix_fmt(enum PixelFormat pix_fmt);
+
 /**
  * Returns the hardware accelerated codec for codec \p codec_id and
  * pixel format \p pix_fmt.