uclibc: fix microblaze runtime error

With binutils 2.29 a runtime error is seen:
Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000100

Backport upstream patch to fix the issue.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>