from_lavc_vid_conv bench tool compat

Fix the benchmark tool build when src/config.h present and CUDA
conversions enabled there. The appropriate CUDA files will be required
if HAVE_LAVC_CUDA_CONV is defined.

Author: MartinPulec

src/libavcodec/from_lavc_vid_conv.c

@@ -59,7 +59,9 @@
 
 #include "color.h"
 #include "compat/qsort_s.h"
+#ifdef HAVE_CONFIG_H
 #include "config.h"       // for HWACC_VDPAU
+#endif
 #include "debug.h"
 #include "host.h"
 #include "hwaccel_vdpau.h"