autotest-tests: force to use gcc to compile a benchmark

clang could not compile iTLB_benchmark_function.c so we need
to use gcc to build this test. upstream bug filed
https://llvm.org/bugs/show_bug.cgi?id=25416

BUG=chromium:552019
TEST=it uses gcc even CC=clang is set.

Change-Id: I2e0ed115d8cf47687e6bb33ed504eddecc7e3765
Reviewed-on: https://chromium-review.googlesource.com/310977
Commit-Ready: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
Reviewed-by: Yunlian Jiang <yunlian@chromium.org>
1 file changed