> ../../../../external/bsd/drm2/dist/drm/i915/intel_ddi.c -o intel_ddi.o
makeoptions i915drmkms "CWARNFLAGS.intel_ddi.c"+="${${ACTIVE_CC} ==
gcc && ${HAVE_GCC:U0} == 7:? -Wno-error=implicit-fallthrough :}"
this is missing from your build some how.
do you have HAVE_GCC set to something not 7?
.mrg.
