GMP 6.1.0 without assembly lacks ‘__gmpn_invert_lib’ on ARM

[Ludovic Courtès]

Hello!

When GMP 6.1.0 is built with --host=none-unknown-linux-gnueabihf on
ARMv7 (the way GCC configures its in-tree GMP, as of GCC 4.9.3),
‘__gmpn_invert_lib’ is missing from the resulting libgmp.a.

--8<---------------cut here---------------start------------->8---
$ nm /gnu/store/v6ipb4br8h6sy9zc82aj464cjcgnv7gl-gmp-6.1.0/lib/libgmp.a |grep __gmpn_invert_limb
nm: mp_clz_tab.o: no symbols
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
         U __gmpn_invert_limb
00000000 T __gmpn_invert_limb
nm: repl-vsnprintf.o: no symbols
--8<---------------cut here---------------end--------------->8---

This seems to be expected, but then it looks as though <gmp-impl.h> was
erroneously referring to it, leading to undefined references, as
reported at <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67728>.

Ideas?

Thanks,
Ludo’.