message: alloy.py: add --shallow-clone option
diff: #!/usr/bin/env python3
  #
  -# Copyright (c) 2013-2022, Intel Corporation
  +# Copyright (c) 2013-2023, Intel Corporation
  # All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  @@ -147,14 +147,10 @@ def checkout_LLVM(component, version_LLVM, target_dir, from_validation, verbose)
  else:
  alloy_error("Unsupported llvm version: " + version_LLVM, 1)
  - try_do_LLVM("clone "+component+" from "+GIT_REPO_BASE+" to "+target_dir+" ",
  - "git clone "+GIT_REPO_BASE+" "+target_dir,
  - from_validation, verbose)
  - if GIT_TAG != "main":
  - os.chdir(target_dir)
  - try_do_LLVM("switch to "+GIT_TAG+" tag ",
  - "git checkout -b "+GIT_TAG+" "+GIT_TAG, from_validation, verbose)
  - os.chdir("..")
  + depth = "" if options.full_checkout else "--depth=1 --shallow-submodules"
  + git_clone_cmd = f"git clone {depth} --branch {GIT_TAG} {GIT_REPO_BASE} {target_dir}"
  + try_do_LLVM(f"clone {component} with tag {GIT_TAG} from {GIT_REPO_BASE} to {target_dir}",
  + git_clone_cmd, from_validation, verbose)
  # ISPC uses LLVM dumps for debug output, so build correctly it requires these functions to be
  # present in LLVM libraries. In LLVM 5.0 they are not there by default and require explicit enabling.
  @@ -945,6 +941,9 @@ if __name__ == '__main__':
  "These options must be used with -b option.")
  llvm_group.add_option('--version', dest='version',
  help='version of llvm to build: 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 trunk. Default: trunk', default="trunk")
  + llvm_group.add_option('--full-checkout', dest='full_checkout', action='store_true', default=False,
  + help=('Disable a shallow clone and checkout a whole LLVM repository.\n'
  + 'By default it clones LLVM with --depth=1 to save space and time'))
  llvm_group.add_option('--with-gcc-toolchain', dest='gcc_toolchain_path',
  help='GCC install dir to use when building clang. It is important to set when ' +
  'you have alternative gcc installation. Note that otherwise gcc from standard ' +
  