Change planar_samples from int16_t to SampleType.

This one was missed in r26174.

Originally committed as revision 26179 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ac3enc.c

@@ -139,7 +139,7 @@ typedef struct AC3EncodeContext {
     int mant1_cnt, mant2_cnt, mant4_cnt;    ///< mantissa counts for bap=1,2,4
     uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
 
-    int16_t **planar_samples;
+    SampleType **planar_samples;
     uint8_t *bap_buffer;
     uint8_t *bap1_buffer;
     CoefType *mdct_coef_buffer;