configure: Fix showcqt fft dependancy

Found-by: Muhammad Faiz <mfcc64@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -2698,6 +2698,8 @@ sab_filter_deps="gpl swscale"
 scale_filter_deps="swscale"
 select_filter_select="pixelutils"
 smartblur_filter_deps="gpl swscale"
+showcqt_filter_deps="avcodec"
+showcqt_filter_select="fft"
 showspectrum_filter_deps="avcodec"
 showspectrum_filter_select="rdft"
 spp_filter_deps="gpl avcodec"