virtualbox-guest-additions-5.0.18 compilation fails

[Kajan]

virtualbox-guest-additions-5.0.18 fails to compile for Gentoo Linux and kernels 4.4/4.5.1

make -j3 HOSTCC=x86_64-pc-linux-gnu-gcc CROSS_COMPILE=x86_64-pc-linux-gnu- 'LDFLAGS=-m elf_x86_64' KERN_DIR=/lib/modules/4.4.0-pf8/build KERNOUT=/lib/modules/4.4.0-pf8/build all 
grep: /lib/modules/4.4.0-pf8/build/include/linux/version.h: No such file or directory
make KBUILD_VERBOSE=1 -C /lib/modules/4.4.0-pf8/build SUBDIRS=/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm SRCROOT=/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm modules
make[1]: Entering directory '/usr/src/linux-4.4_p8-pf'
test -e include/generated/autoconf.h -a -e include/config/auto.conf || (		\
echo >&2;							\
echo >&2 "  ERROR: Kernel configuration is invalid.";		\
echo >&2 "         include/generated/autoconf.h or include/config/auto.conf are missing.";\
echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it.";	\
echo >&2 ;							\
/bin/false)
mkdir -p /var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm/.tmp_versions ; rm -f /var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm/.tmp_versions/*
make -f ./scripts/Makefile.build obj=/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm
make[2]: *** No rule to make target '/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm/vboxvideo_drm.o', needed by '/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm/vboxvideo.o'.  Stop.
Makefile:1384: recipe for target '_module_/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm' failed
make[1]: *** [_module_/var/tmp/portage/x11-drivers/xf86-video-virtualbox-5.0.18/work/vboxvideo_drm] Error 2

[Frank Mehnert]

This is a Gentoo bug! The Makefile of the 5.0.18 Guest Additions is quite different from the 5.0.16 Makefile. No vboxvideo_drm.o is built anymore.