Re: files.conf(5): document compile-with

> 	AMD_C=         ${CC} ${CFLAGS} ${CPPFLAGS} ${AMD_INCLUDES} ${PROF} -c $<
> 
> in Makefile.amd64. overall this would make the compiler invocations
> shorter and drop the explicit rules for the hardfloat amdgpu targets, by
> moving them to the files.conf, e.g.
> 
> file   dev/pci/drm/amd/display/dc/dml/calcs/dcn_calc_auto.c            amdgpu & bios   compile-with "${AMD_C} ${HARDFLOAT_CFLAGS}"

Maybe, but the copying of ${NORMAL_C} and tweaking it seems fragile.
But I'm not sure if it can be done by composing from NORMAL_C, because
the -c $< at the end is positionally sensitive.