.circleci: Copy LLVM from pre-built image (#43038)
Summary:
LLVM builds took a large amount of time and bogged down docker builds in
general. Since we build it the same for everything let's just copy it
from a pre-built image instead of building it from source every time.
Builds are defined in https://github.com/pytorch/builder/pull/491
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43038
Reviewed By: malfet
Differential Revision: D23119513
Pulled By: seemethere
fbshipit-source-id: f44324439d45d97065246caad07c848e261a1ab6
