llvm: Move it to third_party/llvm/src Clone the llvm_project into third_party src location to make for README.chromium and related files. Bug: angleproject:8369 Change-Id: I625eefd8fd883a956985d217f33274ebe7fbe7ed Signed-off-by: Gowtham Tammana <g.tammana@samsung.com> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5111802 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>