Cherry pick upstream patch for aarch64 unsupported reloc.

Bug entry here - https://b.corp.google.com/u/0/issues/25642296

Tested: ./build.py --host "linux" --toolchain aarch64-linux-android

Upstream patch here -

commit 4d2f5d5824be99326c2c3e459c298e338856d8c8
Author: Han Shen <shenhan@google.com>
Date:   Tue Oct 27 15:17:54 2015 -0700

    Patch for PR gold/19042 - unsupported reloc 311/312.

    gold/

        * aarch64.cc (Target_aarch64::Scan::local): Add support for
        reloc 311/312.

Change-Id: If784460c1ebdfb2be1ebdf1486db5eb03c5240a5