IANAL, but by my reading, the GPL does include build scripts as part of the source code, e.g. from GPLv3: "all the source code needed to generate [...] the obj

IANAL, but by my reading, the GPL does include build scripts as part of the source code, e.g. from GPLv3: "all the source code needed to generate [...] the object code and to modify the work, including scripts to control those activities" Presumably this includes things like Makefiles.