[clang] [llvm] test-release.sh: Add a CMake cache file for 3-stage release builds (PR #75903)

[Tom Stellard via cfe-commits]

tstellar wrote:

> Out of curiosity, what's the reason for using 3-stage (rather than 2-stage) build?

I'm trying to replicate what the script currently does which is a 3-stage build.  I also want to add in PGO in the future, which would require 3 stages.

https://github.com/llvm/llvm-project/pull/75903