Fix typos.

Originally committed as revision 26183 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -992,11 +992,11 @@ typedef struct AVPanScan{
     int8_t *ref_index[2];\
 \
     /**\
-     * reordered opaque 64bit (generally a integer or double preccission float \
+     * reordered opaque 64bit (generally an integer or a double precision float\
      * PTS but can be anything). \
      * The user sets AVCodecContext.reordered_opaque to represent the input at\
-     * that time ,\
-     * the decoder reorderes values as needed and sets AVFrame.reordered_opaque\
+     * that time,\
+     * the decoder reorders values as needed and sets AVFrame.reordered_opaque\
      * to exactly one of the values provided by the user through AVCodecContext.reordered_opaque \
      * - encoding: unused\
      * - decoding: Read by user.\