There are a few more failures happen on AArch64 bare-metal recently as we
have enabled more elf tests.

As run_ld_link_exec_tests now always use gcc as linker driver, I think 
it should
start to specify all ccflags as well as ccflags may contain linker 
options for
example spec file.  There was similar fix before

   https://sourceware.org/ml/binutils/2014-10/msg00184.html

Meanwhile one unique test need to do the same thing.

This patch fixed quite a few failures on aarch64 bare-metal linker 
testing, no
regression.

OK for master?

2017-01-20  Jiong Wang  <jiong.wang@arm.com>

         * ld/testsuite/lib/ld-lib.exp (run_ld_link_exec_tests): Append
         board_cflags as gcc is used as linker driver.
         * ld/testsuite/ld-unique/unique.exp: Likewise