binutils-2.26 configure doesn't fall back to 'ar' if it can't find 'x86_64-unknown-linux-gnu-ar'

[Alastair Hughes]

I've tried updating to binutils 2.26, however, it currently fails to build as 
it tries to use "x86_64-unknown-linux-gnu-ar". The old configure script 
(binutils 2.25) noticed that various x86_64-unknown-linux-gnu-* tools did not 
exist, and instead falls back to plain 'ar' (or readelf, or ld, or...), while 
the configure script for binutils 2.26 tries to use the 
x86_64-unknown-linux-gnu-* names anyway.
I can't see anything in the git log that would cause this change - what have I 
missed? Is this a regression?

I've rebuilt 2.25 on my system to check that it was a binutils problem, and can 
attach the logs from both builds if that would help.

Regards,
Alastair Hughes