Hi
The attached patch generates all the makefile targets from a shared include file.
It also allows WORKDIR= to be defined to change where the output is produced.
This makes it easy to replace the actual build commands with something else, in my case docker-rpm-builder. I haven't yet made that neatly configurable/pluggable and I'm not sure I should; it's actually probably simpler to use something completely
separate and just pass the same make macros.
So I probably won't do anything more with this.
Anyway, in case it's useful/interesting, here it is. Apply with "git am".
