https://bugs.winehq.org/show_bug.cgi?id=45435
--- Comment #4 from Alistair Leslie-Hughes leslie_alistair@hotmail.com --- The value for LIBAVUTIL_CFLAGS is set correctly in config.log.
Can you check the file dlls/xaudio2_7/Makefile for LIBAVUTIL_CFLAGS
If its not set, can you run "make distclean", then run configure again. I'm guessing that for some reason the Makefile's haven't been regenerated.