Add DIRECTFB_CFLAGS to SDL_CFLAGS so its cflags will get added to the sdl2.pc
diff --git a/configure.in b/configure.in
index f7537f0..791c870 100644
--- a/configure.in
+++ b/configure.in
@@ -1783,6 +1783,7 @@ AC_MSG_WARN("directfb $directfb_lib")
SUMMARY_video="${SUMMARY_video} directfb"
fi
AC_MSG_RESULT($directfb_shared)
+ SDL_CFLAGS="$SDL_CFLAGS $DIRECTFB_CFLAGS"
have_video=yes
fi
fi