FFT: factor a shuffle out of the inner loop and merge it into fft_permute.

6% faster SSE FFT on Conroe, 2.5% on Penryn.

Signed-off-by: Janne Grunau <janne-ffmpeg@jannau.net>
(cherry picked from commit e6b1ed693a)

libavcodec/arm/fft_init_arm.c

@@ -44,7 +44,7 @@ av_cold void ff_fft_init_arm(FFTContext *s)
         s->imdct_calc   = ff_imdct_calc_neon;
         s->imdct_half   = ff_imdct_half_neon;
         s->mdct_calc    = ff_mdct_calc_neon;
-        s->permutation  = FF_MDCT_PERM_INTERLEAVE;
+        s->mdct_permutation = FF_MDCT_PERM_INTERLEAVE;
     }
 }