hikey-aosp branch
git.linaro.org/uefi/uefi-tools.git recently added support for gcc5
but github.com/96boards-hikey/edk2.git has not, so the build will
break if using a gcc5 version toolchain.
Fixes
http://www.96boards.org/forums/topic/cannot-build-hikey-fw-from-source
until hikey edk2 gets upstreamed.
Signed-off-by: Victor Chong <victor.chong@linaro.org>