When building pnacl with --host-flavor=debug, tools at

../../out/llvm_x86_64_linux_work/Release+Asserts/bin

are not available, so we need a fix to enable source code formatting
with tools from

../../out/llvm_x86_64_linux_debug_work/Debug+Asserts/bin

R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/2081223003 .

Patch from Srdjan Obucina <Srdjan.Obucina@imgtec.com>.