llvm_tools: Fix bug in creating symlink

Pass "-r" to ln to keep the symlink relative rather than
absolute.

BUG=chromium:1041590
TEST=unit tests.

Change-Id: I925df430abd0d25a94e17a06186ee9f503efa264
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2142920
Reviewed-by: George Burgess <gbiv@chromium.org>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
2 files changed