aac: add headers needed for log2f()

Allows compilation of aaccoder.c under cygwin

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Reinhard Tartler <siretart@tauware.de>

(cherry picked from commit 30fe9719344f01a147628e07a8e79a9ccc7e0835)

libavcodec/aaccoder.c

@@ -35,6 +35,7 @@
 #include "aac.h"
 #include "aacenc.h"
 #include "aactab.h"
+#include "libavutil/libm.h"
 
 /** bits needed to code codebook run value for long windows */
 static const uint8_t run_value_bits_long[64] = {

libavcodec/aacsbr.c

@@ -32,6 +32,7 @@
 #include "aacsbrdata.h"
 #include "fft.h"
 #include "aacps.h"
+#include "libavutil/libm.h"
 
 #include <stdint.h>
 #include <float.h>