[Bug lto/78795] LTO causes undefined reference errors when linking with GMP "make check"

[vincent-gcc at vinc17 dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78795

--- Comment #5 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to Markus Trippelsdorf from comment #3)
> Also make sure that nm, ar and ranlib use the liblto_plugin,
> by either using wrappers (gcc-ar, etc.) or setting up a symlink
> to the plugin in lib/bfd-plugins/.

This seems to be the problem. But on a different Debian machine, I could test:
* With GCC 4.7.4: no problems.
* With GCC 4.8.5: no problems.
* With GCC 4.9.4: undefined reference errors.
* With GCC 6.2.1: undefined reference errors.

When I get the undefined reference errors, I can see lots of "plugin needed to
handle lto object" errors with nm and ranlib at least.

So, has anything changed for the use of LTO between 4.8 and 4.9?
Or is this a Debian specific issue?