Did you get your source code from a Subversion repository?
I had the same issue, as i checked out the source code from an unofficial Subversion repository. So I first installed libasound2-dev
and copied the directory /usr/include/alsa
to the directory external/qemu/alsa
as you and Peter Ju proposed. But after that another error occurred:
make: *** No rule to make target 'prebuilt/linux-x86/sdl/lib/libSDL.a', needed by 'out/host/linux-x86/obj/STATIC_LIBRARIES/libSDL_intermediates/libSDL.a'. Stop.
After some research I found out that some static libraries in the prebuilt
folder were missing, because Subversion ignores some specific file extensions. After getting these files, everything worked well...
Don't know if this will do trick in your case but maybe it is the 'missing link' for you or someone else...