[Bug bootstrap/91034] In tree build of gmp fails on Raspberry Pi4 (ARM Cortex A72) with `mls r1,r4,r8,r11' not supported in ARM mode

[andrewm.roberts at sky dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91034

--- Comment #9 from Andrew Roberts <andrewm.roberts at sky dot com> ---
For completeness I've also built gcc 8.3.0 with in tree gmp 6.1.2 using the
newly built 9.1.0. And then in turn used this gcc 8.3.0 to rebuild gcc 9.1.0
with in tree gmp.

So the host gcc 8.3.0 doesn't work building gcc with in tree gmp.
But all the versions I have built (9.1.0 and 8.3.0) build this correctly.