vf_select: Drop a debug av_log with an unchecked double to enum conversion

CC: libav-stable@libav.org
(cherry picked from commit a8d803a320fb08b3ad5db4fffc79abd401206905)
Signed-off-by: Diego Biurrun <diego@biurrun.de>
video4linux2: Avoid a floating point exception

This avoids a segfault in avconv_opt.c:opt_target when trying to
determine the norm.

(cherry picked from commit dc71f1958846bb1d96de43a4603983dc8450cfcc)
Signed-off-by: Diego Biurrun <diego@biurrun.de>
fate: Add dependencies for dct/fft/mdct/rdft tests

(cherry picked from commit 24f45c16224d4c5d482e928676714766ffdda4fc)
Signed-off-by: Diego Biurrun <diego@biurrun.de>