configure: Fix build without libmfx

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -2214,6 +2214,7 @@ hap_decoder_select="snappy texturedsp"
 hap_encoder_deps="libsnappy"
 hap_encoder_select="texturedspenc"
 hevc_decoder_select="bswapdsp cabac golomb videodsp"
+hevc_qsv_encoder_deps="libmfx"
 hevc_qsv_encoder_select="qsvenc"
 huffyuv_decoder_select="bswapdsp huffyuvdsp llviddsp"
 huffyuv_encoder_select="bswapdsp huffman huffyuvencdsp llviddsp"