configure: add missing libfontconfig and libfreetype dependencies to showcqt filter

Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

configure

@@ -3267,6 +3267,7 @@ scale_filter_deps="swscale"
 scale_qsv_filter_deps="libmfx"
 select_filter_select="pixelutils"
 showcqt_filter_deps="avcodec avformat swscale"
+showcqt_filter_suggest="libfontconfig libfreetype"
 showcqt_filter_select="fft"
 showfreqs_filter_deps="avcodec"
 showfreqs_filter_select="fft"