aacenc: Harmonize multiple inclusion guards

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Reviewed-by: Ganesh Ajjanagadde <gajjanag@mit.edu>

libavcodec/aacenc_quantization.h

@@ -25,6 +25,9 @@
  * @author Rostislav Pehlivanov ( atomnuker gmail com )
  */
 
+#ifndef AVCODEC_AACENC_QUANTIZATION_H
+#define AVCODEC_AACENC_QUANTIZATION_H
+
 #include "aactab.h"
 #include "aacenc.h"
 #include "aacenctab.h"
@@ -253,3 +256,5 @@ static inline void quantize_and_encode_band(struct AACEncContext *s, PutBitConte
     quantize_and_encode_band_cost(s, pb, in, out, NULL, size, scale_idx, cb, lambda,
                                   INFINITY, NULL, rtz);
 }
+
+#endif /* AVCODEC_AACENC_QUANTIZATION_H */