Job Failed #72006386
Microblaze doesn't support SSP, the improved SSP check introduced with Buildroot 2018.05  doesn't allow to import Microblaze glibc toolchain generated with Buildroot 2018.02  because SSP support is unconditionally selected for glibc.
With Buildroot 2018.02 and BR2_SSP_REGULAR the compiler complains about ssp support. warning: -fstack-protector not supported for this target
Selecting BR2_TOOLCHAIN_HAS_SSP on Microblaze must not be allowed.
It's not clear why the SSP support is not available for microblaze because gcc_cv_libc_provides_ssp=yes in gcc/config.log. It's probably a bug.
 https://git.buildroot.net/buildroot/commit/?id=c8680956819fae8776d7bd6d1f0e67a7b6436672  https://toolchains.bootlin.com/downloads/releases/toolchains/microblazeel/tarballs/microblazeel--glibc--bleeding-edge-2018.02-1.tar.bz2