libavcodec: Implementation of 32 bit fixed point FFT

Iterative implementation of 32 bit fixed point split-radix FFT.
Max FFT that can be calculated currently is 2^12.

Signed-off-by: Nedeljko Babic <nbabic@mips.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mdct_fixed.c

@@ -17,6 +17,7 @@
  */
 
 #define CONFIG_FFT_FLOAT 0
+#define CONFIG_FFT_FIXED_32 0
 #include "mdct.c"
 
 /* same as ff_mdct_calcw_c with double-width unscaled output */