configure: add pkg-config support for libdcadec

Signed-off-by: Simon Thelen <ffmpeg-dev@c-14.de>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -5012,7 +5012,8 @@ enabled libcelt           && require libcelt celt/celt.h celt_decode -lcelt0 &&
                              { check_lib celt/celt.h celt_decoder_create_custom -lcelt0 ||
                                die "ERROR: libcelt must be installed and version must be >= 0.11.0."; }
 enabled libcaca           && require_pkg_config caca caca.h caca_create_canvas
-enabled libdcadec         && require libdcadec libdcadec/dca_context.h dcadec_context_create -ldcadec
+enabled libdcadec         && { use_pkg_config dcadec libdcadec/dca_context.h dcadec_context_create ||
+                               { require libdcadec libdcadec/dca_context.h dcadec_context_create -ldcadec; }; }
 enabled libfaac           && require2 libfaac "stdint.h faac.h" faacEncGetVersion -lfaac
 enabled libfdk_aac        && require libfdk_aac fdk-aac/aacenc_lib.h aacEncOpen -lfdk-aac
 flite_libs="-lflite_cmu_time_awb -lflite_cmu_us_awb -lflite_cmu_us_kal -lflite_cmu_us_kal16 -lflite_cmu_us_rms -lflite_cmu_us_slt -lflite_usenglish -lflite_cmulex -lflite"