build: Add a script to simplify build flow
Add a build script that support two build flows:
1. Users provide path to an AOSP-like source root. The script auto
resolve LLVM/Bazel dependencies and build artifacts.
2. Users provide path to LLVM clang/Bazel directly.
Also switch to use http_archive() instead of git_repository() as
recommended by Bazel. git_repository() requires git dependencies on host
and for internal developer may even require `gcert` be run first.
Test: Run the script with u-boot-mainline/AOSP.
Bug: b/294059825
Change-Id: Icfa03f2539e42712a5adf47e9792b31c23abda1b
5 files changed
