[lld] [llvm] [DTLTO][LLD][ELF] Add support for Integrated Distributed ThinLTO (PR #142757)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `cross-project-tests,lld` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/19411

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'lld :: ELF/dtlto/files.test' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 6
rm -rf Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp && split-file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\lld\test\ELF\dtlto\files.test Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp && cd Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp
# executed command: rm -rf 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp'
# note: command had no output on stdout or stderr
# executed command: split-file 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\lld\test\ELF\dtlto\files.test' 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp'
# note: command had no output on stdout or stderr
# executed command: cd 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\ELF\dtlto\Output\files.test.tmp'
# note: command had no output on stdout or stderr
# RUN: at line 8
sed 's/@t1/@t2/g' t1.ll > t2.ll
# executed command: sed s/@t1/@t2/g t1.ll
# note: command had no output on stdout or stderr
# RUN: at line 12
z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe -thinlto-bc t1.ll -o t1.bc
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe' -thinlto-bc t1.ll -o t1.bc
# note: command had no output on stdout or stderr
# RUN: at line 13
z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe -thinlto-bc t2.ll -o t2.bc
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe' -thinlto-bc t2.ll -o t2.bc
# note: command had no output on stdout or stderr
# RUN: at line 14
cp t1.bc t3.bc
# executed command: cp t1.bc t3.bc
# note: command had no output on stdout or stderr
# RUN: at line 17
z:\b\llvm-clang-x86_64-sie-win\build\bin\llc.exe t1.ll --filetype=obj -o t1.o
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llc.exe' t1.ll --filetype=obj -o t1.o
# note: command had no output on stdout or stderr
# RUN: at line 18
z:\b\llvm-clang-x86_64-sie-win\build\bin\llc.exe t2.ll --filetype=obj -o t2.o
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llc.exe' t2.ll --filetype=obj -o t2.o
# note: command had no output on stdout or stderr
# RUN: at line 26
echo "t1.bc t2.bc --start-lib t3.bc --end-lib -o my.elf    --thinlto-distributor="C:\Program Files\Python310\python.exe"    --thinlto-distributor-arg=Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm/utils/dtlto/mock.py    --thinlto-distributor-arg=t1.o    --thinlto-distributor-arg=t2.o" > l.rsp
# executed command: echo 't1.bc t2.bc --start-lib t3.bc --end-lib -o my.elf    --thinlto-distributor=C:\Program' 'Files\Python310\python.exe    --thinlto-distributor-arg=Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm/utils/dtlto/mock.py    --thinlto-distributor-arg=t1.o    --thinlto-distributor-arg=t2.o'
# note: command had no output on stdout or stderr
# RUN: at line 34
z:\b\llvm-clang-x86_64-sie-win\build\bin\ld.lld.exe @l.rsp
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\ld.lld.exe' @l.rsp
# .---command stderr------------
# | ld.lld: error: cannot open Files\Python310\python.exe: no such file or directory
# `-----------------------------
# error: command failed with exit status: 1

--
...

```

</details>

https://github.com/llvm/llvm-project/pull/142757