[Buildroot] uboot-tools autobuilder failure

[Matthew Weber]

Hollis, I don't have a machine old enough to debug this failure.
What's weird is the target uboot-tools is being built with a GCC6/7
which should support -std=gnu11, however we get a cc1: error:
unrecognized command line option "-std=gnu11".

http://autobuild.buildroot.net/?reason=uboot-tools-2018.07

Would you mind running a
https://git.busybox.net/buildroot-test/tree/utils/br-reproduce-build
on one of those build hashes and when it fails drop into the output
folder and run a make V=1?  Then paste that back here?

Matt