Summary:
We previously emulated multi-staged builds using two dockerfiles,
native support from Docker allows us to merge them into one,
simplifying our scripts.
For more details about multi-stage builds, see:
https://docs.docker.com/develop/develop-images/multistage-build/
Reviewers: mehdi_amini, klimek, sammccall
Reviewed By: sammccall
Subscribers: llvm-commits, ioeric, cfe-commits
Differential Revision: https://reviews.llvm.org/D44787
llvm-svn: 328503
d95020108c