License copatibility GPLv3+ (w/ Autoconf Exc) AX_PTHREAD

[Hans Spath]

Hello,

I need some help/advice to understand potential licensing issues with 
macros from the GNU autoconf archive.

Specifically I'm interested in AX_PTHREAD, which is GPLv3+ with Autoconf 
Exception (GPLv3+wAE).

As far as I understand it, I can put it in a local "m4/" directory, use 
it from "configure.ac" and then generate a "configure" file. If I 
distribute a tarball that only contains "configure" but neither the 
"m4/" directory or any .ac file, there is no problem, no matter what the 
license of the rest of the project is.

I have a project that mainly consists of GPLv2+, BSD, MIT and 
GPLv2-only(*) licensed code. Is my assumption correct that I can not 
provide tarballs that contain m4/ax_pthread.m4? Can I at least 
distribute configure.ac and other GPLv2+ files in m4/? Or did the 
dependency on the now missing file taint my buildsystem to be GPLv3+wAE?

Does it also mean that I can not put m4/ax_pthread.m4 in a publicly 
accessible git repository of that project?

What would be your advice to deal with this situation?


Alternatively, would you consider relicensing AX_PTHREAD under GPLv2+wAE 
(or an even more permissive license)?

Regards
Hans Spath


(*: these files originate primarily from the linux kernel)