Merge "Don't discard the result of std::unique" into main am: d0210ae77c am: cffa43f6df am: 2e32ff5e4e

Original change: https://android-review.googlesource.com/c/platform/external/clang/+/2755601

Change-Id: Idaa0238e553e495f23a73b76fc981e6f74cb9425
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>