[Clang][Test] Add llvm-lto, llvm-lto2 and llvm-profdata to the tool substitutions list

[SixWeining]

Summary

Similar to issue fixed in D107155, some lit tests invoke llvm-lto,
llvm-lto2 and llvm-profdata without going through the substitution
system. While the test runner correctly picks up these binaries from
the build directory, it doesn't print its absolute path. When copying
the invocations when reproducing test failures, this can result in
command not found: llvm-lto or other erros (caused by using wrong
version of the tool).

This patch adds these tools to the tools variable in
clang/test/lit.cfg.py which will then call add_tool_substitutions.

[dblaikie]

Seems a bit unfortunate that clang tests are using these tools, but fair enough - they clearly are, so suitable to include them here, I guess.

clang/test/lit.cfg.py

 # the build directory holding that tool.  We explicitly specify the directories
 # to search to ensure that we get the tools just built and not some random
 # tools that might happen to be in the user's PATH.
 tool_dirs = [config.clang_tools_dir, config.llvm_tools_dir]
 
 tools = [
     'apinotes-test', 'c-index-test', 'clang-diff', 'clang-format', 'clang-repl', 'clang-offload-packager',
     'clang-tblgen', 'clang-scan-deps', 'opt', 'llvm-ifs', 'yaml2obj', 'clang-linker-wrapper',
+    'llvm-lto', 'llvm-lto2', 'llvm-profdata',
     ToolSubst('%clang_extdef_map', command=FindTool(
         'clang-extdef-mapping'), unresolved='ignore'),
 ]
 
 if config.clang_examples:
     config.available_features.add('examples')
 
 def have_host_jit_feature_support(feature_name):