llvm_tools: update llvm major in non-llvm ebuilds

This CL implements updating the llvm major version in non-llvm ebuilds.
An example of the current behavior (which uprevs the major version only
for the LLVM ebuild) can be seen here:
https://crrev.com/c/3080644/2

BUG=b:196193631
TEST=./update_chromeos_llvm_hash_unittest.py

Change-Id: Icf82f0a8a4a01b255d0eeb242fe139aaa6957920
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3088319
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Commit-Queue: Ryan Beltran <ryanbeltran@chromium.org>
Tested-by: Ryan Beltran <ryanbeltran@chromium.org>
2 files changed